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Time-of-check Time-of-use (TOCTOU) Race Condition

CVE-2026-45804

Low
0/10

Summary

hf_hub_download and snapshot_download are two independent HTTP calls to the Hub, both resolving the repository's default branch (if revision=None) to its current HEAD at call time. There is no atomicity guarantee between them - if the repository is updated between the two calls, they will resolve to different commits and download different content, with no warning displayed to the user. The trust check in download() operates on the content fetched by hf_hub_download (commit A). The snapshot_download call that immediately follows can silently fetch a newer commit (commit B). The config in the newer commit will be the one parsed by _resolve_custom_pipeline_and_cls. This issue affects versions prior to 0.38.0.

  • HIGH
  • NETWORK
  • HIGH
  • UNCHANGED
  • REQUIRED
  • NONE
  • HIGH
  • HIGH

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state.

References

Advisory Timeline

  • Published