Quick answers
- Is CVE-2026-93321 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-93321 being exploited in the wild.
- How severe is CVE-2026-93321?
- Informational severity, published 5 October 2026.
- Which products and versions are affected?
- Moby BuildKit <=0.33.0.
- Is there a fix for CVE-2026-93321?
- Yes: fixed in 0.33.1. Until then: Avoid using external BuildKit frontends from untrusted sources. Dockerfile builds are unaffected by this vulnerability. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-93321 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-93321?
- Check whether you run Moby BuildKit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 0.33.1
Avoid using external BuildKit frontends from untrusted sources. Dockerfile builds are unaffected by this vulnerability.
Technical details
The vulnerability exists in BuildKit's handling of LLB (Low-Level Builder) merge operations with mismatched input counts. An attacker who can supply a malicious LLB definition through an external frontend can trigger an unhandled panic in buildkitd, causing a denial of service. This requires local attack vector or the ability to interact with a BuildKit instance accepting external frontends.
Affected products
- Moby BuildKit <=0.33.0
Timeline
- 2026-09-30: disclosed
- 2026-09-30: patched