Bug 2566543 (CVE-2026-121542)

Summary: CVE-2026-121542 github.com/docker/buildx: Docker Buildx: Information disclosure via filesystem entitlement check bypass
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: amctagga, aoconnor, bniver, flucifre, gmeno, groman, mbenjamin, mhackett, sostapov, vereddy
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Docker Buildx. This vulnerability allows unauthorized file access when a user executes an untrusted Bake build definition. Due to improper filesystem entitlement validation, paths in the same parent directory that share a prefix with the current working directory name can bypass access controls. Consequently, an attacker who supplies a malicious build definition can expose and read local files accessible to the build client without authorization.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-11-03 22:11:25 UTC 
In Docker Buildx versions v0.19.0 through v0.38.0, an untrusted Bake definition may expose files accessible to the Buildx client without the expected fs.read approval. Under certain conditions, paths under the same parent directory as the current working directory whose names use the working directory's basename as a prefix can skip the filesystem entitlement check. Exploitation requires specific matching filenames next to the current project directory. Users who run untrusted Bake definitions may be affected. The issue is fixed in v0.38.1.