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CVE-2026-20040
high
CVSS 8.8
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.
AI summary snake-internal / snake-material-v2
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.
❓ What is the problem
**OS command injection** (CWE-78) exists in Cisco ios-xr.
📍 Affected scope
Cisco ios-xr — .
🔥 Severity
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover
🔧 How to fix
Update to the patched release per vendor advisory.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'ios-xr' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'ios-xr' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で `ios-xr` を grep し、稼働しているサービス・バージョンを把握する。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
References
- CISCO https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-privesc-bF8D5U4W?vs_f=Cisco%20Security%20Advisory%26vs_cat=Security%20Intelligence%26vs_type=RSS%26vs_p=Cisco%20IOS%20XR%20Software%20CLI%20Privilege%20Escalation%20Vulnerabilities%26vs_k=1
- patch [email protected]