CVE-2026-15788

WCOW cache mount source selector resolves NTFS junctions outside of cache root

State: Published
Severity: 5.6 Medium
Published: Jul 20, 2026
Updated: Jul 21, 2026
Reserved: Jul 14, 2026

Description

BuildKit's cache mount source= selector on Windows Container on Windows (WCOW) workers does not detect NTFS directory junctions placed inside the cache root. A build authored by an untrusted user on a WCOW-configured BuildKit daemon can read arbitrary host files reachable to the BuildKit daemon process.

Scores

CVSS	Score	Vector	Source
4.0	5.6 Medium	CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N	Docker

Weaknesses

CWE-59 Improper Link Resolution Before File Access ('Link Following')

Affected Products

Product	Versions
BuildKitmoby	before 0.31.2Affected

References

https://github.com/moby/buildkit/security/advisories/GHSA-388v-wmr2-g2v2vendor-advisory

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