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Vulnerabilities

Vulnerability · CVE-2026-121520

Malicious client could set xattr value outside of BuildKit state directory

Published Nov 3, 2026 · catalog updated Nov 3, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-121520. EPSS is 0.14%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.9
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.14%
Remediation
Advisory link
Affected products
vendor Moby BuildKit

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Moby BuildKitversion unspecified

How to fix CVE-2026-121520

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-121520. EPSS is 0.14%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-22: Path Traversal; CWE-61. EPSS 0.14%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Nov 4, 2026 · BSI CERT-Bund

    Detected

    CVE-2026-121520 is listed by BuildKit: Mehrere Schwachstellen.

Sources

  • BSI CERT-BundGovernment advisoryCVE-2026-121520

    BuildKit: Mehrere Schwachstellen

    wid.cert-bund.de
  • CVE.orgVulnerability recordCVE-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 se

    cve.org
  • Red Hat Security DataVendor advisoryCVE-2026-121520

    github.com/moby/buildkit: BuildKit: Privilege escalation via unauthorized extended file attribute modification

    access.redhat.com

References

Freshness

Last verified in this catalog Nov 4, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Red Hat Security DataNov 5, 2026
  • CVE.orgNov 4, 2026
  • BSI CERT-BundNov 4, 2026