CVE-2026-75593: BuildKit: Malicious client can bypass destination directory validation on local sources upload

Vulnerability summary

CVE-2026-75593 is a high (CVSS 7.2) vulnerability in moby buildkit. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 45.5% of scored vulnerabilities.

Timeline

1. 19-08-2026
   PublishedVulnerability first disclosed.
2. 25-08-2026
   Last modifiedVulnerability information updated.

Description

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to 0.31.2, a custom client can produce such an upload request to the BuildKit daemon that files can escape from the BuildKit-controlled state directory. The client needs to have valid permissions to access BuildKit control API to issue builds, eg., bypass authentication, etc. This issue is fixed in version 0.31.2.

• CWE-22Improper Limitation of a Pathname to a Restricted DirectoryThe product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.