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CVE-2026-41579 low CVSS 3.3

Vulnerability in github.com/opencontainers/runc (CVE-2026-41579)

Summary

Vulnerability in github.com/opencontainers/runc (CVE-2026-41579). Risk of unauthorized operations or information disclosure. Exploitable via setupPtmx. Mitigation: upgrade to 1.5.0-rc.3 or later.

Original description

The description as published by the source.

Impact

When setting up the container rootfs, setupPtmx and setupDevSymlinks call os.Remove and os.Symlink with a filepath.Join string which allow an image with /dev as a symlink to trick runc into deleting files called ptmx on the host or creating a hardcoded set of symlinks with specific names and targets in an arbitrary pre-existing host directory.

Please note that this issue is not exploitable under Docker because it creates a top-level ro layer that masks any malicious /dev symlink present in the container image (this is also done without mounting the lower layers so there is no opportunity for the malicious /dev symlink to trick it into resolving to some other path). Unfortunately, Podman and containerd† do not do this and so users using those higher-level runtimes with runc can be exploited via a malicious image.

This issue mirrors a somewhat similar issue in crun, which was also published recently.

† Actually, at the time the issue was analysed, containerd had dead code that implemented this feature but the implementation contained several security issues that would arguably have made it more exploitable than in runc. Luckily, the code appears to have never been used (at least since 2…

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-2026-41579 has been found in github.com/opencontainers/runc.
Attackers can target a specific entry point like setupPtmx over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.3/10.
What to do: upgrade github.com/opencontainers/runc to 1.5.0-rc.3 or later.
If unsure, ask your IT team or search "github.com/opencontainers/runc CVE-2026-41579" on the vendor's site.

CVE-2026-41579 (github.com/opencontainers/runc) — CWE-61 / CVSS v3 3.3
Attack vector: local / unauthenticated
Attack surface: setupPtmx / setupDevSymlinks / os.Remove / os.Symlink
Patched: 1.5.0-rc.3 — 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 (CWE-61) exists in github.com/opencontainers/runc. Attackers reach the vulnerable code path via setupPtmx without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/opencontainers/runc. Attack surface: setupPtmx / setupDevSymlinks / os.Remove / os.Symlink.

🔥 Severity

Severity: Low (CVSS 3.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 1.5.0-rc.3.

🛡️ 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 'github.com/opencontainers/runc' . 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. 1
    Identify exposure identify 
    grep -r 'github.com/opencontainers/runc' . | 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/opencontainers/runc を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade github.com/opencontainers/runc to 1.5.0-rc.3

    ステージング環境で 1.5.0-rc.3 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. 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

go github.com/opencontainers/runc
[{"type":"SEMVER","events":[{"introduced":"1.5.0-rc.1"},{"fixed":"1.5.0-rc.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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