Vulnerability in github.com/moby/sys/user (CVE-2026-61801)
Summary
Vulnerability in github.com/moby/sys/user (CVE-2026-61801). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 0.4.1 or later.
Original description
The description as published by the source.
A denial-of-service (DoS) vulnerability exists in github.com/moby/sys/user before v0.4.1 when parsing specially crafted user or group database files. An attacker able to supply a malicious /etc/passwd or /etc/group-style file may cause excessive memory consumption, potentially resulting in process termination due to Out Of Memory (OOM) conditions.
This issue is related to containerd [CVE-2026-47262] / GHSA-jpcc-p29g-p8mq, which describes one practical exploitation path through processing untrusted container image content. Applications using github.com/moby/sys/user to parse untrusted user or group database files may be similarly affected.
Impact
github.com/moby/sys/user versions before v0.4.1 do not place sufficient limits on entries while parsing user and group database files. A specially crafted file may cause excessive memory consumption, potentially leading to process termination due to Out Of Memory (OOM) conditions.
Applications that use github.com/moby/sys/user to parse user-supplied or otherwise untrusted /etc/passwd or /etc/group files may be affected. The severity depends on whether an attacker can influence the contents of files being parsed.
Patches
This issue is fixed in github.com/moby/sys/user v0.4.1. Users should upgrade to v0.4.1 or later.
Workarounds
Avoid parsing attacker-controlled /etc/passwd or /etc/group-style files with affected…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
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-2026-61801 has been found in github.com/moby/sys/user.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: upgrade github.com/moby/sys/user to 0.4.1 or later.
If unsure, ask your IT team or search "github.com/moby/sys/user CVE-2026-61801" on the vendor's site.
CVE-2026-61801 (github.com/moby/sys/user) — CWE-400 / CVSS v3 5.5
Attack vector: local / no user interaction
Patched: 0.4.1 — 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 (CWE-400) exists in github.com/moby/sys/user.
Check the vendor advisory for the affected versions of github.com/moby/sys/user.
Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.
Update to 0.4.1.
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 'github.com/moby/sys/user' . 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 'github.com/moby/sys/user' . | 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
github.com/moby/sys/user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 github.com/moby/sys/user to 0.4.1ステージング環境で 0.4.1 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。
-
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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-61801