Time-of-check Time-of-use (TOCTOU) Race Condition Affecting github.com/moby/buildkit/executor/runcexecutor package, versions >=0.31.0 <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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Test your applications- Snyk IDSNYK-GOLANG-GITHUBCOMMOBYBUILDKITEXECUTORRUNCEXECUTOR-20826436
- published11 Oct 2026
- disclosed5 Oct 2026
- creditStanPlatinum, Plucky923, SylvanJu
Introduced: 5 Oct 2026
NewCVE-2026-93315 (opens in a new tab)How to fix?
Upgrade github.com/moby/buildkit/executor/runcexecutor to version 0.33.1 or higher.
Overview
Affected versions of this package are vulnerable to Time-of-check Time-of-use (TOCTOU) Race Condition in the containerd and runc executor run paths. An attacker can make a build succeed, block cleanup, or leave cleanup operating outside the intended rootfs by mutating the injected CA bundle during an exec step when proxy networking with CA injection is enabled. This can cause the build to complete even though the temporary proxy certificate was not removed, leaving the CA bundle in a bad state or causing cleanup to fail after the build step has run.
Workarounds
- Avoid using build sources from untrusted locations; this reduces the chance a build step can mutate the injected proxy CA bundle before cleanup.
- Only enable proxy networking for exec steps when necessary, via BuildKitd TOML config or Buildx Rego policy; this prevents exposure to the proxy CA cleanup disruption path.