Cisco Issues Security Updates for IOS XR Fixing Multiple Critical Vulnerabilities
Cisco Systems has published security updates for its network operating system Cisco IOS XR to remediate multiple vulnerabilities identified through internal investigation.
The updates were released on September 2, 2026, local time. Researchers classified the issues into seven categories and assigned individual CVE identifiers to each. All releases are affected regardless of specific configuration settings.
Critical Vulnerabilities
CVE-2026-20274 stems from improper resource management, leading to buffer overflows and out-of-bounds memory read/write operations. CVE-2026-20279 involves access control deficiencies. Both received a CVSS v3.1 base score of 9.8 and are rated Critical.
High-Severity Issues
- CVE-2026-20278, CVE-2026-20275, and CVE-2026-20280 address command injection and related problems with a base score of 8.8.
- CVE-2026-20276 concerns control flow management weaknesses, scoring 8.6.
- CVE-2026-20277 involves protection mechanism failures, rated 8.2.
No evidence of active exploitation was reported at the time of the advisory. Cisco has made available Software Maintenance Updates (SMU) and intends to incorporate the fixes into future versions 26.3.1 and 26.2.2.
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