CVE-2026-41579
LOWrunc: Malicious image with /dev symlink can trigger limited host filesystem integrity violations
Blast Radius
github.com/opencontainers/runc🐹github.com/opencontainers/runc🐹github.com/opencontainers/runcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
runc is a CLI tool for spawning and running containers according to the OCI specification. In versions prior to 1.3.6, 1.4.0-rc.1, 1.4.0-rc.12, 1.5.0-rc.1, and 1.5.0-rc.1, 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. This issue is not exploitable under Docker, because Docker creates a top-level read-only layer that masks any malicious /dev symlink present in the container image — unlike some other Linux container tooling, whose higher-level runtimes built on runc remain exposed to exploitation via a malicious image. This issue has been fixed in versions 1.3.6, 1.4.3 and 1.5.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/opencontainers/runc | all versions | 1.3.6 |
| 🐹Go | github.com/opencontainers/runc | ≥ 1.4.0&&< 1.4.3 | 1.4.3 |
| 🐹Go | github.com/opencontainers/runc | ≥ 1.5.0-rc.1&&< 1.5.0-rc.3 | 1.5.0-rc.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/opencontainers/runc. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/opencontainers/runc to 1.3.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41579 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-41579 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-41579. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-41579 in your dependencies?
O3 detects CVE-2026-41579 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.