Vulnerability in cpio (UBUNTU-CVE-2026-66485)

Summary

Vulnerability in cpio (UBUNTU-CVE-2026-66485). 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 is vulnerable to an uncontrolled memory allocation in the make_path function at src/makepath.c. The function uses alloca to allocate stack memory based on the length of argpath, which is derived from an archive-controlled pathname during extraction. A malicious cpio archive containing a sufficiently long nested pathname causes an unbounded stack allocation, resulting in a stack overflow and crash of the cpio process. An attacker who can supply a crafted cpio archive to a victim who extracts it can cause a denial of service. This issue has been fixed in commit 3cd514031371d8aeeaf2048aa10103e02831aaa9

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-2026-66485 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-2026-66485" on the vendor's site.

UBUNTU-CVE-2026-66485 (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.

❓ What is the problem

A vulnerability (unclassified) exists in cpio.

📍 Affected scope

Check the vendor advisory for the affected versions of cpio.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.11+dfsg-1ubuntu1.2+esm3.

🛡️ 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 '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

1
Identify 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。
2
Apply 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。
3
Post-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

Ubuntu:Pro:14.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11+dfsg-1ubuntu1.2+esm3"}]}]

Ubuntu:Pro:16.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11+dfsg-5ubuntu1.1+esm2"}]}]

Ubuntu:Pro:18.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.12+dfsg-6ubuntu0.18.04.4+esm1"}]}]

Ubuntu:Pro:20.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.13+dfsg-2ubuntu0.4+esm1"}]}]

Ubuntu:22.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.13+dfsg-7ubuntu0.2"}]}]

Ubuntu:24.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.15+dfsg-1ubuntu2.1"}]}]

Ubuntu:26.04:LTS cpio

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.15+dfsg-2.1ubuntu0.1"}]}]

References

advisory ubuntu.com
report ubuntu.com
report cve.org
report cert.pl
report git.savannah.gnu.org