Improper Validation of Array Index Affecting github.com/moby/buildkit/solver package, versions <0.33.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published11 Oct 2026
- disclosed5 Oct 2026
- creditYanhaoxi
Introduced: 5 Oct 2026
NewCVE-2026-93321 Â (opens in a new tab)How to fix?
Upgrade github.com/moby/buildkit/solver to version 0.33.1 or higher.
Overview
Affected versions of this package are vulnerable to Improper Validation of Array Index through malformed LLB op validation in the solver’s SourceOp and DiffOp handling. An attacker can crash buildkitd by submitting a crafted LLB definition with an input/dependency count mismatch. The affected code in solver/llbsolver/ops and solver/jobs.go processes malicious frontend input without rejecting malformed dependency layouts, allowing the daemon to hit a dependency index panic while scheduling cache maps. When triggered, the buildkitd process terminates and interrupts builds running on that daemon.
Workarounds
- Avoid using external BuildKit frontends from untrusted sources; only run frontends you trust, because a malicious frontend can submit crafted LLB definitions that crash
buildkitd. - Do not expose
buildkitdto untrusted users or inputs that can provide custom LLB/frontend definitions, because limiting who can submit LLB reduces the chance of a dependency-mismatch crash.