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Critical Cisco Nexus 9000 Flaw Lets Unauthenticated Remote Attackers Run Code as Root

Cisco patches critical CVE-2026-20212 (CVSS 9.8) in Nexus 9000 switches allowing unauthenticated remote root code execution, plus IOS XR hardening release.

Cisco released fixes for CVE-2026-20212 (CVSS 9.8), a flaw in 10 Silicon One-based Nexus 9000 switch models that binds a service to an unrestricted IP, leaving TCP ports 43210/43211 reachable in the default Layer 3 VRF and allowing unauthenticated remote attackers to execute code as root; exploitation attempts can also crash the S1HAL process. 45 NX-OS releases (10.3(1) through 10.6(3s)) are affected, with mitigations including infrastructure ACLs, the Live Protect shield lp00031, and fixed releases identified via Cisco's Software Checker. Cisco simultaneously issued an IOS XR hardening release bundling 7 umbrella CVEs, two rated 9.8 (CVE-2026-20274 for memory-safety bugs and CVE-2026-20279 for access-control bugs), affecting all releases with SMUs available for 14 releases and upgrades required for 93 of 111 listed releases. No malicious exploitation was reported as of the September 2 disclosure.

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.

⚡ Weekly Recap: Chrome 0-Day, Router Hijacks, Coder Supply Chain Attack and More

Weekly recap: actively exploited Chrome V8 zero-day, MikroTik RouterOS zero-day chain, Magento StyleSmuggler backdoor, and critical N-able N-central flaws.

Google patched an actively exploited Chrome V8 type confusion zero-day, CVE-2026-85046 (CVSS 8.8), the sixth exploited Chrome zero-day of 2026. CERT Polska warned of the MikroTrick exploit chain (CVE-2026-67276 and CVE-2026-86060, CVSS 9.2) giving unauthenticated full control of MikroTik RouterOS devices via SSH, observed since September 2. Sansec disclosed the StyleSmuggler Magento/Adobe Commerce zero-day used since September 4 to inject a Rust backdoor into online stores, while N-able patched three critical N-central flaws (CVE-2026-86206, CVE-2026-86207, and CVE-2026-86218, CVSS 10.0) with Huntress observing likely exploitation. Elastic and Morphisec also detailed RevStealer, an information stealer spread via game cheats and a fake Claude Desktop app.

The Hacker News · 9d agoExploit / PoC in the wildCVE-2026-85046CVE-2026-86206CVE-2026-86207+7 CVEs

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.

Cisco Advance Notification for Publication of September 2, 2026, Security Advisories

Cisco PSIRT published September 2, 2026 advisories including critical IOS XR hardening fixes and a Nexus 9000 remote code execution flaw.

Cisco's PSIRT released its September 2, 2026 batch of security advisories, including a Cisco IOS XR Software security hardening release bundling six CVEs (CVE-2026-20274 through CVE-2026-20280) rated critical with CVSS 9.8. A separate critical (CVSS 9.8) remote code execution vulnerability, CVE-2026-20212, affects Nexus 9000 Series switches with Silicon One, and a high-severity (CVSS 7.5) denial-of-service flaw, CVE-2026-20281, affects the Desk Phone 9800 Series and related SIP phones. Administrators should review the advisories and prioritize patching the critical-rated issues.