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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-15788
StatePUBLISHED
AssignerDocker
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-20 20:16:43 UTC
Updated2026-07-21 13:17:02 UTC
DescriptionBuildKit'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.

Risk And Classification

Primary CVSS: v4.0 5.6 MEDIUM from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.001450000 probability, percentile 0.042220000 (date 2026-07-21)

Problem Types: CWE-59 | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.6MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.6MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Confidentiality
High
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Moby BuildKit affected 0.31.2 semver Windows

References

ReferenceSourceLinkTags
github.com/moby/buildkit/security/advisories/GHSA-388v-wmr2-g2v2 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Junyi Liu (mosskappa) (en)

Additional Advisory Data

Workarounds

CNA: Use trusted build sources.

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