Vulnerability in cpio (UBUNTU-CVE-2026-66484)
Summary
Vulnerability in cpio (UBUNTU-CVE-2026-66484). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 2.11+dfsg-1ubuntu1.2+esm3 or later.
Original description
The description as published by the source.
GNU cpio contains a Path Traversal vulnerability in its tar archive extraction functionality. When extracting a tar archive in copy-in mode with the --no-absolute-filenames option, the extracted file name is normalized but the tar hard-link target is passed to the link_to_name function without equivalent sanitization before calling link function. A tar archive provided by an attacker, containing a hard-link entry whose linkname is set to an absolute path outside the extraction directory, can cause cpio to create a hard link to an existing file outside the intended extraction directory, breaking the expected guarantee of --no-absolute-filenames and allowing archive-controlled linkage to external files. This issue has been fixed in commit e2b9cbdd3354d2b1569b7390d1bc15c1930559ad
Source: OSV.dev (Open Source Vulnerabilities) OSV
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 UBUNTU-CVE-2026-66484 has been found in cpio.
Risk of unauthorized operations or information disclosure.
What to do: upgrade cpio to 2.11+dfsg-1ubuntu1.2+esm3 or later.
If unsure, ask your IT team or search "cpio UBUNTU-CVE-2026-66484" on the vendor's site.
UBUNTU-CVE-2026-66484 (cpio)
Patched: 2.11+dfsg-1ubuntu1.2+esm3 — apply immediately
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.
A vulnerability (unclassified) exists in cpio.
Check the vendor advisory for the affected versions of cpio.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 2.11+dfsg-1ubuntu1.2+esm3.
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. Run grep -r 'cpio' . against your dependency files (package-lock.json, requirements.txt, go.sum) 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
grep -r 'cpio' . | 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
cpioを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade cpio to 2.11+dfsg-1ubuntu1.2+esm3ステージング環境で 2.11+dfsg-1ubuntu1.2+esm3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-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。
Affected packages
References
- advisory ubuntu.com
- report ubuntu.com
- report cve.org
- report cert.pl
- report git.savannah.gnu.org