CVE-2026-15788

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

HIGH

7.5

CVSS Score

Published: July 20, 2026 at 07:12 PM UTC

Updated: October 24, 2026 at 08:10 PM UTC

2 products affected across 2 vendorsBuildkitBuildKit

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Severity

HIGH7.5

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Buildkit · Mobyproject

95%

v < 0.31.2

Affected range stops below 0.31.2, so it looks safe — our inference, not a vendor statement

BuildKit · Moby

90%

0 ≤ v < 0.31.2

Affected range stops below 0.31.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://github.com/moby/buildkit/security/advisories/GHSA-388v-wmr2-g2v2

References (1)

Vendor Advisory

Source: cverecord

https://github.com/moby/buildkit/security/advisories/GHSA-388v-wmr2-g2v2

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: NONE
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-59

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