Is there a public exploit for CVE-2026-121520?

No public exploit for CVE-2026-121520 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-121520?

CVE-2026-121520 scores CVSS 4.5 (v4.0), rated medium.

What does CVE-2026-121520 affect?

CVE-2026-121520 affects moby buildkit.

4.5 Medium

In BuildKit versions prior to v0.34.1, a malicious client with access to the BuildKit control APIs can submit a build request that sets an…

CVE-2026-121520

In BuildKit versions prior to v0.34.1, a malicious client with access to the BuildKit control APIs can submit a build request that sets an extended attribute on a file outside the BuildKit state directory. Extended attributes in the trusted. or security. namespaces may also be set, potentially giving a program on the host elevated privileges. This issue affects build services that accept build requests from untrusted users. The issue is fixed in v0.34.1.

Assessment

CVSS: 4.5 (v4.0)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 3 November 2026
Last updated: 3 November 2026
Affected: moby · buildkit
Assigner: Docker

CVSS vectorCVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:H

At the source

EUVD (ENISA)

References

https://github.com/moby/buildkit/security/advisories/GHSA-w26x-xg27-7qjc

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