Actively exploited Citrix NetScaler flaw CVE-2026-8452, patched in June, now added to CISA KEV; attackers deploy web shells and run discovery commands.
CISA added CVE-2026-8452, a memory overflow vulnerability in Citrix NetScaler ADC/Gateway, to its Known Exploited Vulnerabilities catalog on August 26, 2026, giving federal agencies until August 29 to remediate. Citrix disclosed and patched the flaw on June 30, 2026 in versions 14.1-72.61, 13.1-63.18, and 13.1-37.272. watchTowr Labs found the flaw can be chained into unauthenticated remote code execution and released a PoC on August 14. Previdian and Defused reported exploitation with web shells named x.php and z.php from at least three unique source IPs.
CISA adds actively exploited flaws in Microsoft IKE, SharePoint, VMware vCenter, and macOS Screen Sharing to KEV catalog, due August 21.
CISA added four vulnerabilities to its Known Exploited Vulnerabilities catalog: CVE-2026-33824 (Windows IKE remote code execution, CVSS 9.8), CVE-2026-55040 (SharePoint JWT authentication bypass, CVSS 9.1), CVE-2026-59310 (VMware vCenter Syslog path traversal, CVSS 9.8), and CVE-2026-65400 (macOS Screen Sharing improper authentication). The SharePoint flaw combines four weaknesses including alg:none JWT forging to impersonate any user, with Defused researchers observing attackers using Rapid7's PoC against honeypots. The Dutch NCSC confirmed active exploitation of the macOS Screen Sharing flaw on August 15, 2026. Federal agencies must patch by August 21, 2026.
Attackers are actively exploiting critical SharePoint authentication bypass CVE-2026-55040 (CVSS 9.1) days after Rapid7 released a public PoC.
CVE-2026-55040 is a critical authentication bypass (CVSS 9.1) in SharePoint Server Subscription Edition that lets unauthenticated attackers forge JWT tokens and impersonate any user, including administrators. Microsoft patched it in July 2026 Patch Tuesday, but Rapid7 published a technical write-up and Python PoC on GitHub on August 12, and Defused quickly observed attackers running the PoC against SharePoint honeypots. KEVIntel recorded 12 exploitation attempts since July 19, with eight occurring on August 12-13 from IP addresses in Hong Kong, Japan, the Netherlands, Taiwan and the U.S. Admin-level SharePoint access exposes documents and data modification and can serve as a foothold into broader Microsoft 365 infrastructure; unpatched instances should apply the July update immediately.
Authentication Bypass in Microsoft SharePoint Server
Microsoft SharePoint Server is affected by a weak authentication vulnerability (CWE-1390) that allows an unauthorized attacker to bypass a security feature over a network. Per the CVSS vector, exploitation requires no privileges and no user interaction with low attack complexity, so any unauthenticated attacker with network access to a vulnerable server can trigger it remotely. Impact to confidentiality and integrity is rated high (CVSS 9.1, critical), meaning the bypass effectively grants the attacker access that authentication should have prevented, with no direct availability impact. All organizations running on-premises Microsoft SharePoint Server are potentially affected; the source data does not specify affected version ranges or fixed builds, so defenders should consult Microsoft's advisory for those details. The flaw is under active exploitation: a public proof-of-concept is available on GitHub, attackers began exploiting it after the PoC went public, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-18 (EPSS ~40%, 99th percentile; ransomware association unknown).
Unauthenticated Path Traversal RCE in Broadcom VMware vCenter Server Syslog
CVE-2026-59310 is a directory traversal (CWE-22) vulnerability in the Syslog server component of VMware vCenter Server, rated critical at CVSS 9.8. It can be triggered over the network without authentication or user interaction, allowing a malicious actor with network access to vCenter to achieve arbitrary code execution. An attacker who exploits it gains code execution on the vCenter appliance, and reported campaigns show it has been used to establish persistent remote access and, by a suspected China-nexus actor, to deploy Babuk ransomware. Any organization running an affected version of vCenter Server is exposed, especially where the management interface is reachable from the internet; the available data does not specify affected version ranges. Exploitation is confirmed in the wild: CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-08-18, it was reportedly exploited just five days after disclosure, and EPSS estimates a 45.9% probability of exploitation within 30 days (99th percentile).
· Broadcom (VMware) vCenter Server KEV ransomwarelarge
Unauthenticated Double-Free RCE in Microsoft Windows IKE Extension
A double-free memory-corruption flaw (CWE-415) in the Microsoft Windows Internet Key Exchange (IKE) service extension allows a remote, unauthenticated attacker to trigger the bug with crafted network traffic, with no privileges or user interaction required. Successful exploitation yields remote code execution with full system impact, reflected in the critical 9.8 CVSS score (high confidentiality, integrity, and availability). The vulnerable IKE component is present in Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1), and Windows Server 2016, 2019, and 2022 (including 23H2), which ship it as a built-in feature. CISA added the flaw to the Known Exploited Vulnerabilities catalog on 2026-08-18, and security reporting confirms it is being actively exploited in the wild, though ransomware use is not yet confirmed. No public proof-of-concept is known, but the high EPSS score (72.7%, 99th percentile) signals a very strong likelihood of imminent or ongoing exploitation.
· Microsoft Windows 10 1607 · Microsoft Windows 10 1809 KEVmass
Authentication Bypass in Apple macOS Screen Sharing
CVE-2026-65400 is a critical (CVSS 9.8) improper authentication flaw (CWE-287) in Apple macOS's Screen Sharing service, caused by an authentication state-management defect. An attacker who can reach a vulnerable Mac's Screen Sharing service over the network can authenticate without valid credentials, gaining full remote access with high impact to confidentiality, integrity, and availability. All three currently supported macOS branches are affected: Sequoia, Sonoma, and Tahoe, in versions prior to the fixed releases. The flaw is being actively exploited on the internet, with public reporting that attackers use the bypass to deploy Monero cryptominers, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-18. EPSS estimates a 9.9% probability of exploitation within 30 days (95th percentile).
· Apple macOS (Screen Sharing service) supported macOS releases prior to the fixed builds listed below · Apple macOS Sequoia all versions prior to 15.7.9 KEVmass
Unauthenticated .NET Deserialization RCE in Ajax.NET Professional (ajaxpro.2)
Ajax.NET Professional (distributed as the ajaxpro.2 package) is vulnerable to insecure deserialization (CWE-502): it deserializes arbitrary .NET classes supplied by the client without validating which types may be instantiated. Because AjaxPro exposes HTTP endpoints for browser-to-server AJAX calls, a remote, unauthenticated attacker can send a crafted serialized payload to any reachable AjaxPro endpoint and abuse .NET deserialization gadget chains to execute code on the server. Successful exploitation yields full remote code execution with high impact on confidentiality, integrity, and availability (CVSS 3.1 score of 9.8, network vector, no privileges or user interaction required). Any application running any version of ajaxpro.2 / Ajax.NET Professional is affected; the provided data specifies no fixed version, so defenders must rely on vendor guidance for patched releases. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-26, carries an EPSS 30-day exploitation probability of 83.6%, has public PoC code available, and Talos Intelligence reporting links it to the Chinese-speaking threat actor UAT-10147, which deploys the SPECTRE malware with an EDR bypass and a Linux rootkit in post-compromise operations.
· michaelschwarz (ajaxpro.2 project) ajaxpro.2 (package) All versions are vulnerable; no fixed version specified in the provided data · michaelschwarz Ajax.NET Professional All versions are vulnerable; no fixed version specified in the provided data KEV PoC ×2
Remote Code Execution in Microsoft SQL Server 2016 and 2017
CVE-2019-1068 is a remote code execution vulnerability in Microsoft SQL Server caused by improper handling of the processing of internal functions (CWE-20, improper input validation). An attacker who can reach SQL Server over the network with low-privileged credentials can trigger the flawed code path and execute arbitrary code, gaining high confidentiality, integrity, and availability impact on the database host. Any organization running affected Microsoft SQL Server versions — including SQL Server 2016 and SQL Server 2017 — is affected. The flaw carries a high EPSS score (52.8% probability of exploitation within 30 days, 99th percentile) and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-26, with headlines reporting it being exploited in active attacks. No public proof-of-concept is known, but the in-the-wild exploitation documented by CISA makes patching urgent; the fix shipped in Microsoft's July 2019 Patch Tuesday security updates.
· Microsoft SQL Server · microsoft SQL Server 2016 KEVmass
Memory Buffer Overflow in Citrix NetScaler ADC/Gateway Exploited in the Wild
CVE-2026-8452 is a memory buffer overflow (CWE-119) in Citrix NetScaler ADC and NetScaler Gateway that applies when the appliance is configured as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy) or as an AAA virtual server. The flaw is reachable over the network without authentication (CVSS 4.0: AV:N/PR:N), so an unauthenticated attacker can trigger it remotely. Successful exploitation causes unpredictable or erroneous appliance behavior and denial of service, and the high confidentiality score suggests possible disclosure of memory contents; some reporting suggests pre-authentication remote code execution may be possible, though the vendor description emphasizes DoS. Organizations running affected NetScaler appliances in a Gateway or AAA role — a very common configuration for remote access to Citrix virtual apps and desktops — are potentially exposed. The flaw was added to CISA's KEV catalog on 2026-08-26 and is reported as exploited in the wild, with headlines noting the flaw was already patched before exploitation was confirmed.
Out-of-Bounds Write in Linux Kernel watch_queue Enables Local Privilege Escalation
CVE-2022-0995 is an out-of-bounds (OOB) memory write in the Linux kernel's watch_queue event notification subsystem (CWE-787) that can overwrite parts of kernel state. A local user can trigger it through the watch_queue interface, for example by supplying a crafted event filter definition, causing the kernel to write beyond allocated memory when event notifications are processed. Successful exploitation may allow the local user to gain privileged (kernel/root) access or crash the system, yielding high impact on confidentiality, integrity, and availability (CVSS 3.1: 7.8, local attack vector). Affected systems include mainstream Linux kernels (Fedora is explicitly listed) and NetApp HCI appliance firmware products that ship the affected kernel. The flaw is confirmed exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-26, two public proof-of-concepts are available, and EPSS puts 30-day exploitation probability at 9.5% (95th percentile), though ransomware use is unconfirmed.
· Linux kernel Kernels shipping the watch_queue event notification subsystem prior to patched/upstream fixes (see distribution advisories for exact affected and fixed versions · Fedora Project Fedora Fedora releases with affected kernel packages prior to the issued kernel updates (see Fedora/Red Hat advisories) KEV PoC ×2mass
Local Privilege Escalation via Symlink Attack in Red Hat ABRT
CVE-2015-5287 is a privilege escalation flaw in Red Hat's Automatic Bug Reporting Tool (ABRT) in which a local user with certain permissions can gain elevated privileges via a symlink attack against a file with a predictable name. Exploitation requires local access to an affected system; an attacker who triggers the flawed file-handling behavior can elevate their privileges on that machine. It affects deployments running ABRT, which ships by default with Red Hat Enterprise Linux and related distributions, including systems that may now be end-of-life or end-of-service. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-08-26, indicating exploitation has been observed in the wild, though no public proof-of-concept is known and ransomware use is unknown. EPSS estimates a 5.0% probability of exploitation within 30 days (92nd percentile).
· Red Hat Automatic Bug Reporting Tool (ABRT) KEVmass
Race Condition in Red Hat libuser Allows Local Privilege Escalation
CVE-2015-3246 is a race condition in Red Hat's libuser, the user-management library used by utilities that modify system accounts, that can cause corruption of the /etc/passwd file during concurrent account updates. An authenticated local user who triggers the race — typically by racing account-modification operations against one another — can desynchronize or corrupt the passwd file. Successful exploitation yields either a denial-of-service condition on the host or, in the privilege-escalation case, elevated (root-level) access by manipulating entries in /etc/passwd. Any Red Hat system shipping the vulnerable libuser library is affected, with risk concentrated on multi-user servers where untrusted local accounts exist. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-26, indicating it is being exploited in the wild, and EPSS assigns it an 8.8% probability of exploitation within 30 days (95th percentile); ransomware use is unknown and no public proof-of-concept is cataloged.
· Red Hat libuser Affected versions not enumerated in the source data; applies to libuser as shipped with Red Hat distributions and remediated via Red Hat security updates KEVmass
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