Skip to content
Fencer Intel
medium 6.9

CVE-2026-93321 json

Malformed LLB file operation can crash buildkitd

published last mo. modified last mo. also EUVD-2026-92820 , GHSA-fjj4-h6vf-m9hj

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository moby/buildkit. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
6.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

A malicious frontend can submit an LLB definition that causes buildkitd to panic and terminate, interrupting all builds running on that daemon.

Patch / fix

  • mobyproject buildkit 0.33.1

Is CVE-2026-93321 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-93321 updated cvss 6.2

github.com/moby/buildkit: BuildKit: Denial of Service via crafted low-level builder definition

  • Red Hat Quay 3 quay/quay-builder-rhel8, quay/quay-builder-rhel9
    affected: workaround, no fix available “Avoid using custom or untrusted BuildKit frontends, and restrict build submission access to verified users. Isolate build daemon instances per tenant to prevent cross-tenant build interruption.”
  • Red Hat Hardened Images podman 6.1.3-1.hum1, buildah 1.45.1-1.hum1, trivy 0.74.0-0.4.hum1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 6.9 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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

Affected products

  • moby BuildKit

Classification

Weakness
  • CWE-129 Improper Validation of Array Index

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of moby/buildkit published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.