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Cisco bundles fixes for multiple vulnerabilities, some critical, into one patch
Cisco patched seven IOS XR vulnerabilities, two rated CVSS 9.8, allowing unauthenticated remote code execution and root access on carrier routers; no exploitation observed.
Cisco released fixes for seven internally discovered vulnerabilities in IOS XR, its Linux-based network operating system for carrier-grade routers. Two flaws, CVE-2026-20274 and CVE-2026-20279, are rated CVSS 9.8 (critical) and involve lifetime resource control issues that can enable unauthenticated remote code execution with root access; the other five are rated 8.2-8.8 and cover buffer overflows, access control failures, and out-of-bounds access. All IOS XR releases including IOS XR7 are affected regardless of configuration, no workarounds exist, and remediation requires software maintenance upgrades (SMUs) or fixed releases 26.2.2/26.3.1. Cisco says the flaws are not known to be actively exploited, but experts urge immediate patching of internet-facing and core routing systems, citing parallels with Salt Typhoon tradecraft.
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Cisco searched for IOS XR bugs and found so many it rolled them into an update release
Cisco patched three critical flaws, including CVE-2026-20212 unauthenticated remote root code execution in Nexus 9000 switches; no exploitation observed yet.
Cisco disclosed three critical-rated flaws found during a comprehensive internal security review. CVE-2026-20274 and CVE-2026-20279, both CVSS 9.8, affect the IOS XR carrier-grade operating system and are fixed in newly released versions. CVE-2026-20212 lets unauthenticated remote attackers execute code with root privileges on some Nexus 9000 Series Switches by reaching TCP ports 43210 and 43211 in the default Layer 3 VRF; no software fix exists yet, only infrastructure ACL mitigations. Cisco says it has not observed attacks against these flaws.
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China-Linked Fire Ant Hijacks Cisco Routers to Steal Credentials and Blind Security Logs
China-nexus espionage group Fire Ant compromised Cisco IOS XR routers and TACACS servers to harvest credentials, capture traffic and suppress logs.
Sygnia investigated an intrusion in which Fire Ant expanded beyond VMware hypervisors to Cisco IOS XR routers, TACACS servers and Linux management hosts. The actor deployed purpose-built router implants that hid a GRE tunnel, filtered log messages, captured PCAPs uploaded to external FTP servers, and used TacTap to inject a library into tac_plus and steal TACACS credentials obfuscated with a single-byte XOR key of 0xEF. A Linux backdoor named BridgeAgent masqueraded as a Zabbix agent, persisted via a root systemd unit, disguised itself as /usr/bin/gnome-shell and received commands over TLS on port 443. The group also used Medusa and REPTILE rootkits, SSH backdoors and renamed binaries impersonating SentinelOne and Cybereason agents, while suppressing logs, disabling SELinux and rewriting login history. Sygnia assesses strong overlap with UNC3886 and published IoCs.
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China-linked Fire Ant Hides Inside Trusted Infrastructure
China-linked Fire Ant backdoored Cisco IOS XR routers, injected TACACS libraries to steal credentials, and rewrote logs across infrastructure targets.
Sygnia reports the China-linked espionage group Fire Ant compromised Cisco IOS XR routers with purpose-built malware, injected a library into the TACACS authentication daemon to capture live credential material, and manipulated syslog so only messages containing 'Health' were logged. The group used GRE tunnel interfaces with no commit history, rewrote wtmp/utmp/btmp login records, and deployed dormant deep backdoors on Linux systems — one disguised as a SentinelOne agent, another activated by raw network traffic carrying a magic string. Code-level overlap with UNC3886 tooling suggests evolution of that China-nexus cluster's TACACS credential-collection techniques, and Fire Ant used compromised infrastructure to scan SSH, RDP and web ports toward high-value networks.
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China's 'Fire Ant' campaign used compromised Cisco routers as platform for more attacks
Sygnia links the China-nexus Fire Ant campaign to UNC3886, showing hackers weaponized compromised Cisco IOS XR routers for espionage and wider intrusions.
Sygnia's Fire Ant report details Chinese hackers compromising Cisco IOS XR routers, TACACS+ authentication servers and management infrastructure to capture traffic, harvest credentials and stage attacks on high-value and critical infrastructure networks. The group, which overlaps with Mandiant's UNC3886, developed custom router malware for persistence, hid logs, deleted files and tampered with firewall rules, and remained active in 2026 after Sygnia's 2025 disclosure. The activity aligns with prior Chinese campaigns against Cisco devices, including Volt Typhoon and Salt Typhoon operations.
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CISA Flags Exploited Cisco, Citrix, Fortinet Flaws, Sets Sept. 12 Federal Patch Deadline
CISA adds actively exploited Cisco, Citrix, and Fortinet edge-device flaws to KEV catalog, ordering federal agencies to patch by September 12, 2026.
CISA added CVE-2026-20079 (Cisco Secure Firewall Management Center authentication bypass, CVSS 10.0), CVE-2026-19490 (Citrix NetScaler ADC/Gateway authentication bypass, CVSS 9.3), and CVE-2025-25249 (FortiOS heap buffer overflow, CVSS 7.3) to the Known Exploited Vulnerabilities catalog with a September 12, 2026 deadline for FCEB agencies. Cisco confirmed active exploitation of CVE-2026-20079 in August 2026, while Previdian honeypots logged 56 NetScaler exploitation attempts since September 3. SOCRadar attributes Fortinet exploitation to a financially motivated Russian-speaking actor deploying the PivotC2 Node.js RAT, infecting 178 of over 3,000 targeted IP addresses, mostly in the US.
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September 2026 Patch Tuesday roundup: Plugs for two zero day holes among almost 1,000 fixes in Windows
Microsoft's September 2026 Patch Tuesday ships 964 fixes including two exploited Windows zero-days (CVE-2026-85880, CVE-2026-81963) and a wormable DNS RCE.
Microsoft's September 2026 Patch Tuesday includes 964 Microsoft vulnerabilities requiring customer action, a record attributed to AI-assisted bug discovery, plus 174 third-party/open-source and 23 Chromium/Edge CVEs. Two zero-days are exploited in the wild: CVE-2026-85880, a Windows ALPC heap overflow enabling AppContainer sandbox escape and privilege escalation, and CVE-2026-81963, a Windows Update Stack escalation to SYSTEM. CVE-2026-69730, an unauthenticated Windows DNS RCE, is not yet exploited but Microsoft expects exploitation, and roughly 20 bugs could be wormable. Separately, SAP issued a critical CVSS 10.0 fix for the EPP component used in S/4HANA and NetWeaver.
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Organizations Urged to Fix 41 Vulnerabilities Added to CISA’s Catalog of Exploited Flaws
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