Vulnerability in libarchive (CVE-2026-4426)
Summary
Vulnerability in libarchive (CVE-2026-4426). Risk of unauthorized operations or information disclosure. Exploitable via pz_log2_bs.
Original description
The description as published by the source.
A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (pz_log2_bs) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this by supplying a specially crafted ISO file. This can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition.
Source: NIST National Vulnerability Database 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-2026-4426 has been found in libarchive.
Attackers can target a specific entry point like pz_log2_bs over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "libarchive CVE-2026-4426" on the vendor's site.
CVE-2026-4426 (libarchive) — CWE-1335 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: pz_log2_bs
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 (CWE-1335) exists in libarchive. Attackers reach the vulnerable code path via pz_log2_bs without authentication.
Check the vendor advisory for the affected versions of libarchive. Attack surface: pz_log2_bs.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
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. Run grep -r 'libarchive' . 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
-
1Identify exposure identify
grep -r 'libarchive' . | 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
libarchiveを grep し、稼働しているサービス・バージョンを把握する。 -
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。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-4426 libarchive Fixed in: 3.4.3-2+deb11u4
- Ubuntu UBUNTU-CVE-2026-4426 libarchive Fixed in: 3.1.2-7ubuntu2.8+esm5
References
- advisory secalert@redhat.com
- advisory secalert@redhat.com
- patch secalert@redhat.com
- web secalert@redhat.com