OS Command Injection in Cisco Ios Xr (CVE-2026-20040)
Summary
OS command injection in Cisco Ios Xr (CVE-2026-20040). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
Multiple vulnerabilities in Cisco IOS XR Software could allow an authenticated, local attacker to execute commands as root on an underlying operating system or gain full administrative control of an affected device. For more information about these vulnerabilities, see the Details section of this advisory. Cisco has released software updates that address these vulnerabilities. A workaround is available for one of the vulnerabilities. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-privesc-bF8D5U4W This advisory is part of the March 2026 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication. Security Impact Rating: High CVE: CVE-2026-20040,CVE-2026-20046
Source: Cisco Security Advisories NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-20040 has been found in Cisco Ios Xr.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Cisco Ios Xr CVE-2026-20040" on the vendor's site.
CVE-2026-20040 (Cisco Ios Xr) — CWE-78 / CVSS v3 8.8
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
OS command injection (CWE-78) exists in Cisco Ios Xr.
Check the vendor advisory for the affected versions of Cisco Ios Xr.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Cisco Ios Xr を使っているサービスとバージョンを洗い出す。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- CISCO sec.cloudapps.cisco.com
- patch psirt@cisco.com