opencontainers runc up to 1.3.5/1.4.2 symlink

Summaryinfo

A vulnerability was found in opencontainers runc up to 1.3.5/1.4.2 and classified as critical. The affected element is an unknown function. The manipulation results in symlink. This vulnerability is reported as CVE-2026-41579. The attack requires a local approach. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in opencontainers runc up to 1.3.5/1.4.2. Affected is an unknown code. The manipulation with an unknown input leads to a symlink vulnerability. CWE is classifying the issue as CWE-61. The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-41579 since 04/21/2026. The exploitability is told to be easy. The attack needs to be approached locally. There are neither technical details nor an exploit publicly available.

Upgrading to version 1.3.6, 1.4.3 or 1.5.0-rc.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-40859). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Virtualization Software

Vendor

• opencontainers

Name

• runc

Version

• 1.3.0
• 1.3.1
• 1.3.2
• 1.3.3
• 1.3.4
• 1.3.5
• 1.4.0
• 1.4.1
• 1.4.2

License

• open-source

Website

• Product: https://github.com/opencontainers/runc/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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