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Citrix NetScaler zero-day exploited in the wild, patch is available (CVE-2023-3519)
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Week in review: Linux rootkit deployed on F5 BIG-IP APM devices, Cisco FMC bugs exploited
Weekly roundup: Cisco FMC and N-able N-central zero-days exploited in the wild, MikroTik RouterOS hijacks, Microsoft Patch Tuesday ships two exploited zero-days.
State-sponsored and financially-motivated attackers are actively exploiting CVE-2026-20079, a critical authentication bypass in Cisco Secure Firewall Management Center (FMC), alongside CVE-2026-20316. N-able issued an emergency hotfix for CVE-2026-86218, a critical pre-auth RCE in the N-central RMM platform exploited in the wild. CERT Polska disclosed six RouterOS vulnerabilities being chained to hijack internet-exposed MikroTik devices. Microsoft's September 2026 Patch Tuesday shipped a record patch count including two zero-days, while roughly 67,000 Trezor customers faced phishing after a shipping-partner breach and researchers privately disclosed a zero-click WeChat worm to Tencent.
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Attackers Exploit Critical Cisco FMC Flaw to deploy Qilin ransomware
Three threat groups, including Qilin ransomware operators, exploit critical Cisco FMC flaws CVE-2026-20079 and CVE-2026-20316 for root access, credential theft, and ransomware.
Cisco Talos identified three post-compromise clusters exploiting recently patched Cisco Secure Firewall Management Center flaws. UAT-12197 deploys JSP web shells and harvests credentials; UAT-11823 (with Sandworm-overlapping tooling) installs Cyclops Blink for persistence; UAT-11988 (Qilin) uses static credentials, extensive reconnaissance, SOCKS5 proxies, reverse-SSH tunnels, AV killers, and ransomware deployment. CISA added CVE-2026-20079 to the KEV catalog with a September 12, 2026 patch deadline for federal agencies; Cisco urges immediate hotfix application.
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CISA Adds Citrix NetScaler CVE-2025-5777 to KEV Catalog as Active Exploits Target Enterprises
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U.S. CISA adds Adminer, Cisco IOS, Fortra GoAnywhere MFT, Libraesva ESG, and Sudo flaws to its Known Exploited Vulnerabilities catalog
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Coruna iOS Exploit Kit Uses 23 Exploits Across Five Chains Targeting iOS 13
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PaperCut warns of hackers using printer management software flaw in attacks
PaperCut warns of active exploitation of CVE-2026-82078 and CVE-2026-81578 in NG/MF print management software used by universities, corporations, and governments.
PaperCut issued an emergency advisory saying vulnerabilities in PaperCut NG and MF, tracked as CVE-2026-82078 and CVE-2026-81578 with severity scores above 8.8, are under active exploitation with confirmed customer incidents. Huntress reported at least two customers impacted, and an initial patch was revised with input from Huntress and watchTowr researchers. PaperCut software is widely deployed at universities, corporations, and governments managing printers from Canon, Epson, Xerox, and Brother, and the vendor urged removing server web interfaces from the public internet. Previous PaperCut flaws were used by ransomware gangs like Bl00dy and Clop, and CISA has warned the education sector is particularly exposed.
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Telerik UI Padding-Oracle Bug Chained to Unauthenticated RCE — Public Exploit Released
TantoSec published a working exploit chaining a Telerik UI padding oracle to unauthenticated RCE; Progress patched the flaws in July.
TantoSec's Marcio Almeida released a full exploit chain and tooling for the RadAsyncUpload control in Telerik UI for ASP.NET AJAX, turning a padding oracle (CVE-2026-13182) into unauthenticated RCE via an unguarded type-resolution flaw (CVE-2026-13181, CVSS 8.1). Exploitation requires a rendered RadAsyncUpload handler and an explicit non-default encryption key, and took roughly 127,000 oracle requests (about an hour) in lab testing. Versions 2010.1.309 through 2026.2.519 are affected; Progress fixed the chain in 2026.2.708 on July 8, 2026, and no in-the-wild exploitation has been confirmed. A separate RCE chain in RadPersistenceManager and RadDockLayout (CVE-2026-13185, -13186, -13190) was also patched but has no public exploit.
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Week in review: Google fixes yet another Chrome zero-day exploit, YouTube as a cybercrime channel
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Threat Brief: Atlassian Confluence Remote Code Execution Vulnerability (CVE-2022
Unauthenticated Confluence RCE CVE-2022-26134 was exploited in the wild; Volexity observed intrusions and Cerber ransomware on unpatched servers.
Volexity identified exploitation of CVE-2022-26134, an unauthenticated remote code execution vulnerability in Atlassian Confluence Server and Data Center, during Memorial Day weekend 2022, with Atlassian issuing a patch. Cortex Xpanse found 19,707 potentially affected Confluence instances, concentrated in the US, Germany, China, and Russia, plus 1,251 end-of-life versions exposed. Unit 42 and Cortex Managed Threat Hunting observed successful exploitation leading to reconnaissance commands and a Cerber ransomware deployment that was blocked by Cortex XDR. A public PoC has increased exploitation risk.
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Week in review: VirusTotal data leak, Citrix NetScaler zero-day exploitation
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Critical macOS, SharePoint, vCenter, and Microsoft IKE Flaws Under Active Exploitation
CISA added four critical actively exploited flaws to KEV: macOS Screen Sharing, SharePoint, VMware vCenter, and Microsoft IKE, with APT and ransomware use.
CISA added CVE-2026-65400 (macOS Screen Sharing, CVSS 9.8), CVE-2026-55040 (SharePoint, CVSS 9.1), CVE-2026-59310 (VMware vCenter, CVSS 9.8) and CVE-2026-33824 (Microsoft IKE Service Extensions, CVSS 9.8) to the KEV catalog. The macOS flaw was abused to deliver a Monero miner, while the vCenter bug was exploited by a suspected China-nexus APT to install reverse_ssh backdoors and Babuk-derived ransomware across 361 victim IPs in 47 countries. Unit 42 linked CVE-2026-33824 to a Chinese-speaking actor running an AI-enabled campaign using DeepSeek. FCEB agencies must patch by August 21, 2026 under BOD 26-04.
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CISA Warns of Fortinet Heap-based Buffer Overflow Flaw Exploited in Attacks
CISA added actively exploited Fortinet CVE-2025-25249, a critical heap-based buffer overflow in FortiOS, FortiSwitchManager, and FortiSASE, to its KEV catalog.
CVE-2025-25249 is a heap-based buffer overflow (CWE-122/CWE-787) allowing unauthorized code execution by sending specially crafted packets. CISA added it to the Known Exploited Vulnerabilities catalog on September 9, 2026, with a September 12 remediation deadline for federal agencies under BOD 26-04 and mandatory forensic triage of affected environments. Internet-facing Fortinet firewalls and SASE platforms are a likely foothold for credential theft, persistence, and lateral movement; ransomware use is currently listed as unknown.
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Active exploitation of Cisco Secure Firewall Management Center vulnerabilities
Cisco Talos reports in-the-wild exploitation of critical FMC flaw CVE-2026-20079 by three clusters including a Sandworm-linked APT and Qilin ransomware affiliates.
Cisco Talos is tracking active exploitation of CVE-2026-20079 (CVSS 10.0), an authentication bypass in Cisco Secure Firewall Management Center that lets unauthenticated remote attackers execute scripts and obtain root access, and CVE-2026-20316 (CVSS 5.3), which permits low-privileged logins and can be chained for privilege escalation. Talos identified three post-compromise clusters: UAT-12197 deploying JSP web shells and a JAR command executor for credential theft; UAT-11823, an APT overlapping with Sandworm, deploying a Netcat reverse shell and Cyclops Blink malware; and UAT-11988, assessed as a ransomware operator with TTPs consistent with Qilin affiliates. Hotfixes are available, with a comprehensive hardening release due the week of September 14, 2026.
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