Incomplete path traversal fixes in awslabs/tough before tough-v0.22.0 allow remote authenticated users with delegated signing authority to write files outside intended output directories via absolute target names in copytarget/linktarget, symlinked parent directories in savetarget, or symlinked metadata filenames in SignedRole::write, because write paths trust the joined destination path without post-resolution containment verification.

We recommend you upgrade to tough-v0.22.0 / tuftool-v0.15.0.

Summary Missing expiration, hash, and length enforcement in delegated metadata validation in awslabs/tough before tough-v0.22.0 allows remote authenticated users with delegated signing authority to bypass TUF specification integrity checks for delegated targets metadata and poison the local metadata cache, because loaddelegations does not apply the same validation checks as the top-level targets metadata path.

Impact The tough library, prior to 0.22.0, does not properly verify delegated target metadata. It allows someone with write access to the metadata to serve expired or otherwise invalid targets from a TUF repository which tough will then trust rather than reject.

Impacted Versions: tough 0.9.0 through 0.21.x, tuftool through 0.14.x

Patches This issue has been addressed in tough version 0.22.0 and tuftool version 0.15.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds No workarounds to this issue are known.

References CVE-2026-6967 If there are any questions or comments about this advisory, please contact [AWS/Amazon] Security via the vulnerability reporting page or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.

Acknowledgement

Amazon Web Services Labs would like to thank Oleh Konko of 1seal for collaborating on this issue through the coordinated vulnerability disclosure process.