MikroTik patches six RouterOS flaws, including the actively exploited MikroTrick SSH chain (CVE-2026-67276, CVE-2026-86060) enabling unauthenticated full router takeover.
MikroTik released patches in RouterOS 7.25 beta 3, 7.24.2, 7.23.4, and 6.49.21 for six vulnerabilities found by CERT Polska, affecting the SSH server/client, bandwidth-test service, X.509 handling, and WebFig. CVE-2026-67276, an RSA public-key validation flaw in the SSH server, lets an attacker who knows a username and key modulus authenticate as that user; CVE-2026-86060 then escalates privileges to root via special-character username handling. CERT Polska confirmed attackers are exploiting the chain to take full control of RouterOS devices with SSH exposed to the internet. Shadowserver Foundation scans show over 122,500 devices with internet-reachable SSH, concentrated in Brazil, the US, and Indonesia.
Sophos details PoisonedRefresh, a fileless Linux rootkit that injects a memory-resident PHP web shell into F5 BIG-IP APM after exploitation of CVE-2025-53521.
On September 8, 2026, SophosLabs published an analysis of Linux/Agnt-IC (dubbed PoisonedRefresh by ESET) found in compromised F5 BIG-IP Access Policy Manager environments. Initial access leverages CVE-2025-53521, an unauthenticated RCE in BIG-IP APM when an access policy is configured on a virtual server; F5 confirmed exploitation and links the activity to cluster c05d5254, while Shadowserver observed 795 exposed vulnerable endpoints. A first stage hidden in a modified umount binary modifies /usr/sbin/httpd and SELinux configuration and embeds itself in BIG-IP upgrade images for persistence. The second-stage ELF intercepts __libc_start_main, hooks apr_dso_load, and injects a PHP web shell into libphp memory via mmap manipulation, leaving no disk artifacts, and exposes a /bin/bash shell via a local UNIX domain socket instead of a TCP port.
Sophos analyzed a Linux rootkit on F5 BIG-IP APM devices that injects a fileless PHP web shell, likely after CVE-2025-53521 exploitation.
Sophos analyzed a Linux rootkit targeting F5 BIG-IP APM environments, also tracked by ESET as PoisonedRefresh, which hijacks Apache's apr_dso_load module loader to inject a fileless PHP web shell into memory. The implant intercepts __libc_start_main, hides strings with RC4, creates a password-protected local UNIX socket backdoor for interactive Bash access, and persists across BIG-IP upgrade images while modifying SELinux configuration. It is likely a second-stage payload following exploitation of CVE-2025-53521, a critical RCE flaw F5 reclassified from a DoS issue in March. The ShadowServer Foundation tracked 795 F5 BIG-IP APM endpoints exposed online.
MikroTik patches six RouterOS flaws; two chained as MikroTrick are actively exploited via SSH to fully compromise exposed routers.
MikroTik released patches for six RouterOS vulnerabilities, including actively exploited MikroTrick chain: CVE-2026-67276 (9.2, SSH auth bypass) and CVE-2026-86060 (9.2, privilege manipulation), plus CVE-2026-67277 (8.8). CERT Poland confirms exploitation since September 2, creating an 'ops' account from IPs 82.192.72.4 and 103.102.31.18. Fixed in RouterOS 7.25beta3, 7.24.2, 7.23.4, and 6.49.21; Shadowserver found 120,000+ SSH-exposed MikroTik devices.
A ransomware gang hit Florida's St. Johns River Water Management District as CISA warned of IRGC-linked CyberAv3ngers attacks on exposed Unitronics water-sector PLCs.
The St. Johns River Water Management District, which oversees Florida drinking-water supply planning, confirmed suspicious activity in its IT environment and said containment measures were implemented; a ransomware gang claimed the attack and shared samples of stolen data. Separately, CISA, FBI, NSA, EPA and Israel's INCD warned that IRGC-affiliated CyberAv3ngers are actively compromising Israeli-made Unitronics Vision Series PLCs in the water sector using default credentials since at least November 22. The group, motivated by opposition to Israel-linked products, defaces controller interfaces and could cause deeper cyber-physical effects. Shadowserver found at least 539 Unitronics PLC instances still exposed online, and CNN reported fewer than 10 US water facilities faced recent attacks.
Attackers actively exploit a MikroTik RouterOS SSH authentication bypass and privilege escalation chain, dubbed MikroTrick, to fully hijack internet-exposed routers.
Poland's CERT, with help from GPT-5.5-cyber and GPT-5.6-sol, discovered and confirmed active exploitation of a MikroTik RouterOS chain dubbed MikroTrick: SSH authentication bypass CVE-2026-67276 (incomplete RSA public key validation) chained with privilege escalation CVE-2026-86060 (crafted usernames granting full administrative privileges). A third flaw, CVE-2026-67277, allows unauthenticated kernel memory leaks or router crashes via the bandwidth-test service. Fixes shipped September 3 in RouterOS 7.25beta3, 7.24.2, 7.23.4, and 6.49.21, adding a startup compromise-detection mechanism. Shadowserver data showed 122,500 MikroTik devices with exposed SSH interfaces as of September 5, and the CERT published IoCs including two attacker IP addresses.
Help Net Security week-in-review roundup: Claude infostealer lockouts, record Patch Tuesday, McKesson breach, SonicWall zero-days, PaperCut attacks.
This Help Net Security weekly roundup aggregates prior stories: Anthropic locking out Claude users after infostealer-compromised login sessions, August 2026 Patch Tuesday's 398 resolved CVEs, ShinyHunters' claim of 284 million stolen patient records from McKesson, active exploitation of SonicWall SMA 1000 zero-days (CVE-2026-83548/83549), Sangoma Switchvox SQL injection exploitation (CVE-2026-9586), and attackers planting RATs on compromised PaperCut servers. It also covers FBI OAuth phishing warnings, a Spring Ring vishing campaign abusing Microsoft Teams, and a fake Claude Opus 5 GitHub repo delivering RevStealer infostealer.
US and European authorities, with CrowdStrike and Shadowserver, disrupted the 20-year-old Sality peer-to-peer botnet, severing 15,000+ infected machines from operators.
US and European authorities disrupted the Sality botnet, active since at least 2003, in an operation involving the DOJ, CrowdStrike, the Shadowserver Foundation and agencies in Bulgaria, Hungary and Romania. Researchers reverse-engineered the botnet's peer-to-peer architecture and injected false data into infected machines' 'super peer' lists, cutting more than 15,000 systems off from their operators. For the past eight years Sality primarily distributed EggJagger, malware that replaces clipboard cryptocurrency addresses and is estimated to have netted the operator at least $150,000. No arrests were announced, and CrowdStrike assesses the operator works from Russia's Bashkortostan region.
Law enforcement, CrowdStrike, and Shadowserver sinkholed the 23-year-old Sality P2P botnet, cutting 15,000+ infected machines from its operator.
Sality, active since 2003 as a file-infecting virus with two P2P networks (versions 3 and 4), distributed credential thieves, spam, proxies, and DDoS payloads, and most recently delivered the EggJagger clipboard hijacker that swapped cryptocurrency wallet addresses for at least $150,000 in operator profit. A coordinated sinkhole operation replaced the botnet's super-peer list with defender-controlled sinkholes, and investigators in the US, Bulgaria, Hungary, and Romania seized payload domains. The Shadowserver Foundation is coordinating ISP and CERT notifications to infected device owners.
About 22,000 Microsoft Exchange servers remain unpatched against critical auth bypass CVE-2026-62911 as a working exploit circulates online.
CVE-2026-62911 is a critical authentication bypass by capture-replay in Microsoft Exchange Server that allows an authorized attacker to elevate privileges over the network, with a CVSS score of 8.0. Microsoft patched the flaw on August 11, 2026, but Shadowserver Foundation scans show roughly 22,000 servers unpatched, with the US (6,200) and Germany (5,100) leading; BSI reports 85% of on-premises Exchange servers in Germany are still vulnerable. The Netherlands' NCSC-NL flagged that a working exploit is circulating, and Exchange 2016/2019 require the Extended Security Updates program for fixes.
Law enforcement and CrowdStrike disrupted the 23-year-old Sality P2P botnet, isolating 15,000+ infected machines and seizing linked domains.
International law enforcement, working with CrowdStrike and the Shadowserver Foundation, executed a peer-to-peer sinkhole operation against Sality, a botnet active since 2003 that delivered malware to more than 15,000 machines worldwide. Sality's primary payload for eight years was EggJagger, a clipboard hijacker that swaps copied bitcoin and ethereum wallet addresses with attacker-controlled ones, yielding at least $150,000 in stolen cryptocurrency. The US Justice Department, FBI, and DoD Office of Inspector General's Defense Criminal Investigative Service seized Sality-linked domains, with parallel action in Bulgaria, Hungary, and Romania. The Shadowserver Foundation is coordinating with ISPs and CSIRTs to identify infections and notify victims.
Help Net Security's weekly digest highlights 274 compromised Zimbra servers, Gitea and Citrix NetScaler KEV additions, a PaperCut zero-day, and a suspected Iran-linked power plant attack.
The roundup reports at least 274 internet-facing Zimbra instances compromised via CVE-2026-73570, critical Gitea CVE-2026-60004 added to CISA's KEV catalog after exploitation began, and previously patched Citrix NetScaler flaw CVE-2026-8452 exploited in the wild. It also covers PaperCut NG/MF zero-day attacks, a suspected Iran-linked shutdown of a UK power plant, an FBI seizure of domains tied to a China-linked group that hit NASA, DOJ and the Senate, a cyberattack disrupting Boston Scientific, and the Manchester Airports Group breach. Additional items include Chameleon SEO poisoning phishing, Android car head unit proxy botnet malware, ReliaQuest social engineering by ShinyHunters, fake OpenAI Codex macOS malware, and AI-related workforce and supply chain interviews.
CERT Polska and CISA report active exploitation of Zimbra RCE CVE-2026-73570, with 267 instances compromised per Shadowserver.
CVE-2026-73570 (CVSS 8.9) enables unauthenticated command injection and remote code execution in Zimbra Collaboration before 10.1.20 when the optional zimbra-snmp package is installed and SNMP notifications are enabled, via crafted SMTP requests. CISA added the flaw to its KEV catalog on August 21, 2026, with a federal patch deadline of August 24. The Shadowserver Foundation counted 267 compromised instances as of August 24, 2026, led by the US (46), Sweden (21), France (20) and Germany (17). Separately, Russia-linked Laundry Bear has weaponized Zimbra stored XSS CVE-2025-66376 against Western government and commercial mail servers since at least July 2025, delivering the ZimReaper payload.
Attackers are exploiting unpatched Zimbra servers via CVE-2026-73570; 274 instances compromised, and CISA added the flaw to its KEV catalog.
The Shadowserver Foundation counted at least 274 compromised internet-facing Zimbra Collaboration Suite instances exploited through CVE-2026-73570, up from 155 on August 20. The unauthenticated code injection flaw affects servers with the optional zimbra-snmp package and SNMP notifications enabled, allowing arbitrary OS command execution via crafted SMTP requests. Synacor patched the issue in ZCS v10.1.20 on July 20, 2026, and at least 8,200 instances remain unpatched. CISA added the flaw to its Known Exploited Vulnerabilities catalog and gave US federal civilian agencies three days to remediate and check for compromise.
Argument-Injection Flaw in MikroTik RouterOS SSH Login Enables Privilege Escalation
CVE-2026-86060 is an argument-injection flaw (CWE-88) in MikroTik RouterOS's SSH login path: when a login supplies a username beginning with a prohibited character, the RouterOS login helper mishandles the argument, allowing the trusted RouterOS policy mask to be changed and privileges to be escalated. An unauthenticated attacker only needs the ability to reach the router's SSH service, since exploitation happens during the SSH login process itself. By altering the policy mask the attacker gains elevated rights on the device, and news reports indicate attackers have used this technique — including logins with usernames such as '-2' — as part of chains that take over routers without needing a password. Any RouterOS deployment running versions before the fixes (6.49.21 Long-term, 7.23.4 Long-term, 7.24.2 Stable) with SSH enabled or reachable is affected, with internet-exposed SSH at highest risk. Multiple outlets report the RouterOS flaws are being actively exploited in the wild, although no public proof-of-concept is known and the flaw is not yet in CISA KEV.
· MikroTik RouterOS v6 (Long-term channel) versions prior to 6.49.21 (fixed in 6.49.21) · MikroTik RouterOS v7 (Long-term channel) versions prior to 7.23.4 (fixed in 7.23.4) KEV PoC ×2mass
Unauthenticated OS Command Injection RCE in Synacor Zimbra Collaboration Suite
CVE-2026-73570 is an OS command injection vulnerability (CWE-78) in Synacor Zimbra Collaboration Suite (ZCS) before 10.1.20, caused by improper sanitization of untrusted input during SNMP notification processing. It is triggered when the optional zimbra-snmp package is installed and SNMP notifications are enabled: an unauthenticated attacker sends specially crafted SMTP requests that the flawed notification path turns into execution of arbitrary operating system commands. Successful exploitation runs commands as the Zimbra user, giving attackers control of the mail server's service account with high confidentiality and integrity impact across the host. Only ZCS deployments running the optional SNMP component with notifications enabled are vulnerable; other Zimbra installs are not exposed to this specific flaw. The flaw is under active exploitation: CISA added it to the KEV catalog on 2026-08-21, Poland's CERT has warned of in-the-wild attacks, unpatched Zimbra servers are reported compromised, and two public proof-of-concept exploits exist.
· Synacor Zimbra Collaboration Suite (ZCS) before 10.1.20 (when the optional zimbra-snmp package is installed and SNMP notifications are enabled) KEV PoC ×4large
SSH RSA Authorized-Key Bypass in MikroTik RouterOS 7.x
MikroTik RouterOS 7.x fails to compare the complete RSA public key when matching an SSH authentication attempt against an authorized user key, checking the key type and modulus but omitting the exponent. Because RouterOS verifies the signature against the client-supplied key, an attacker who knows the modulus of an authorized RSA key can present a key with exponent 1 and a forged signature and be accepted as that user without possessing the private key. Successful exploitation opens an SSH command channel as the target user, giving the attacker control of the router without a password or key. Only the RouterOS 7.x branch is affected, with fixes released in 7.23.4 (Long-term) and 7.24.2 (Stable). A public proof-of-concept is available and related reporting describes active campaigns hijacking MikroTik routers using chained RouterOS flaws, though this CVE is not in CISA KEV and its 30-day EPSS probability is low (0.2%).
· MikroTik RouterOS 7.x branch prior to 7.23.4 (Long-term) and 7.24.2 (Stable)mass
Stack-Based Buffer Overflow in F5 BIG-IP APM Enables Unauthenticated RCE
CVE-2025-53521 is a stack-based buffer overflow (CWE-121) in F5 BIG-IP's Access Policy Manager (APM) that allows remote code execution. The flaw is triggered when a virtual server is configured with an APM access policy and receives specific malicious network traffic; no authentication or user interaction is required per the CVSS 4.0 vector. An attacker who exploits it gains remote code execution on the BIG-IP device, and in observed intrusions attackers have deployed a fileless Linux rootkit (dubbed 'PoisonedRefresh') that injects a PHP web shell into server memory to evade disk-based scanning. Any F5 BIG-IP deployment with an APM access policy configured on a virtual server is potentially affected; versions that have reached End of Technical Support are not evaluated by the vendor. The vulnerability is being actively exploited in the wild — it was added to CISA's Known Exploited Vulnerabilities catalog on 2026-03-27, with active exploitation and in-memory malware campaigns confirmed in press reports, though ransomware use is unknown.
Unauthenticated Kernel Crash and Memory Leak in MikroTik RouterOS btest
CVE-2026-67277 is a missing-authentication flaw (CWE-306) in the bandwidth-test (btest) service of MikroTik RouterOS: the service accepts a "related" btest connection before the primary session has completed authentication, so an unauthenticated remote client can start an IPv4 UDP bandwidth test. When the test runs with "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer, leaking a small amount of kernel memory, and a separate unchecked, inverted packet-size interval causes an unsigned integer underflow that produces anomalously large fragmented output capable of restarting the RouterOS kernel. An unauthenticated network attacker therefore gains limited information disclosure and, more significantly, a remote denial of service through repeated router crashes, with no credentials or user interaction required (CVSS 4.0: 8.8 High). Any MikroTik device running an unpatched RouterOS version with the bandwidth-test server enabled and reachable from an untrusted network is affected. No public PoC or CISA KEV listing exists for this CVE and EPSS is low (0.4%), but it is part of the batch of RouterOS fixes in MikroTik advisory AV26-887 that attackers have recently chained to hijack routers, so in-the-wild exploitation of the flaw set is reported.
· MikroTik RouterOS (Long-term channel, v6) All versions prior to 6.49.21 (fixed in 6.49.21) · MikroTik RouterOS (Long-term channel, v7) All versions prior to 7.23.4 (fixed in 7.23.4) KEV PoC mass
Capture-Replay Authentication Bypass in Microsoft Exchange Server
Microsoft Exchange Server contains an authentication bypass flaw (CWE-294) in which captured authentication material can be replayed, allowing an authorized attacker to elevate privileges over a network. Per the CVSS vector, the attack is network-based with low complexity but requires the attacker to already hold low privileges and some user interaction, and success yields high impact on confidentiality, integrity, and availability. Affected products include on-premises Exchange Server and Exchange Server Subscription Edition, though specific vulnerable version ranges are not specified in the available data. Public scans indicate nearly 22,000 Exchange servers remain exposed to the flaw following the August 2026 Patch Tuesday fixes. No in-the-wild exploitation, public proof-of-concept, or KEV listing is known; the bug was demonstrated at Pwn2Own (ZDI-26-534) and carries an EPSS estimate of 1.3% probability of exploitation within 30 days.
· microsoft exchange server · microsoft exchange server subscription editionlarge
Pre-Authentication SSRF in SonicWall SMA1000 Appliance Workplace Interface
CVE-2026-83548 is a critical (CVSS 3.1 score 10.0) server-side request forgery (SSRF) vulnerability in the Workplace interface of SonicWall SMA1000 appliances, caused by an unintended alternate access path (unprotected alternate channel, CWE-441; SSRF, CWE-918). Because it is pre-authentication, any remote unauthenticated attacker who can reach the interface can trigger it and gain unauthorized access to sensitive functionality and perform unauthorized operations. CISA lists all SonicWall SMA1000 appliances as affected, with CPE data naming the SMA 8200v and SMA 6210/7210 firmware; internet-exposed units are at highest risk. The flaw is being actively exploited in the wild: it was added to CISA's Known Exploited Vulnerabilities catalog on 2026-09-02 alongside companion zero-day CVE-2026-83549, which reporting suggests may form an attack chain with this SSRF. Exploitation probability is elevated (EPSS 4.7%, 91st percentile) and no public proof-of-concept is known.
Cross-Site Scripting in Microsoft Exchange Server Actively Exploited by Laundry Bear
CVE-2026-42897 is an improper-neutralization flaw (CWE-79) in Microsoft Exchange Server that lets an unauthenticated remote attacker perform cross-site scripting and carry out spoofing. Per the CVSS vector (AV:N/PR:N/UI:R), exploitation requires a victim to interact with attacker-controlled content — reported attacks by the Russian actor Laundry Bear (TA488) trigger when a crafted email is opened in Exchange's webmail interface (Outlook Web Access). The attacker gains the ability to spoof the victim within their webmail session, and reported intrusions show mailbox access persisting even after organizations rotate credentials. Any organization running on-premises Microsoft Exchange Server or Exchange Server Subscription Edition is potentially exposed, particularly those publishing webmail to the internet; specific affected version ranges are not provided in the available data. Exploitation is confirmed in the wild: the flaw was added to CISA KEV on 2026-05-15 and carries a very high EPSS score of 71.2%, though no public proof-of-concept is known.
· Microsoft Exchange Server · Microsoft Exchange Server Subscription Edition KEVlarge
Unauthenticated Arbitrary File Read in MikroTik RouterOS WebFig (CVE-2026-67281)
RouterOS WebFig's /jsproxy handler contains an unauthenticated file-read flaw: a newly allocated session keeps a stale, uninitialized principal pointer that is later used to authorize file access (CWE-824), combined with a path-traversal issue (CWE-22). An unauthenticated attacker who can reach the web interface first shapes the heap allocator so the uninitialized pointer resolves with sufficient rights, then submits an encrypted URI containing parent-directory components to escape the WebFig file namespace. This lets the attacker read root-owned files on the router, including configuration stores that contain credentials, which could enable further compromise. Only MikroTik RouterOS 7.x before 7.23.4 (Long-term) and 7.24.2 (Stable) is affected. No public proof-of-concept, KEV listing, or confirmed in-the-wild exploitation of this flaw is known (EPSS ~0.4%), although recent reporting notes MikroTik patches being chained in router-hijack campaigns generally.
· MikroTik RouterOS (WebFig /jsproxy) 7.x branch prior to 7.23.4 (Long-term) and 7.24.2 (Stable); fixed in 7.23.4 and 7.24.2mass
X.509 Signature Forgery Enables TLS Impersonation in MikroTik RouterOS 7.x
MikroTik RouterOS 7.x improperly verifies RSA/PKCS#1 v1.5 signatures when validating X.509 certificate chains, accepting malformed signatures (CWE-347, Improper Verification of Cryptographic Signature). Because the RouterOS trust store includes a root CA whose public key uses the small exponent e=3, an attacker who can control or redirect one of the router's outbound TLS connections (for example via a network man-in-the-middle position, DNS hijacking, or a compromised upstream path) can forge an intermediate CA signed with the root's public key, without ever holding its private key, and mint trusted certificates for arbitrary hostnames. This lets the attacker impersonate TLS servers the router connects to, with low confidentiality and integrity impact per the CVSS 4.0 score of 6.3 (medium), which reflects the network vector, no privileges required, but a high attack requirement of holding such a network position. Any deployment running RouterOS 7.x before 7.23.4 (Long-term) or 7.24.2 (Stable) is affected, spanning home/SOHO, enterprise, and ISP/WISP infrastructure; the 6.x branch is not listed as affected. No public proof-of-concept is known, the issue is not in CISA's KEV, and EPSS gives a 0.2% probability of exploitation within 30 days, although related headlines note other MikroTik flaws have recently been chained to hack routers.
· MikroTik RouterOS 7.x before 7.23.4 (Long-term) and before 7.24.2 (Stable); the 6.x branch is not affectedmass
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