CVE-2026-6967: awslabs/tough is Missing Delegated Metadata Validation
Affects toughSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium : upgrade to 0.22.0 when convenient.
Data as of 27 Oct 2026, 00:07 UTC
- Patch
- Available – fixed in 0.22.0, 0.15.0
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:LExploitation evidence
Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade tough to 0.22.0; tuftool to 0.15.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| crates.iotough | Affected
| Fixed in
|
| crates.iotuftool | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### 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 load_delegations 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](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [aws-security@amazon.com](mailto: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.
References
- github.com/awslabs/tough/security/advisories/GHSA-4v58-8p28-2rq3 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-6967 (opens in a new tab)
- aws.amazon.com/security/security-bulletins/2026-019-aws (opens in a new tab)
- crates.io/crates/tough/0.22.0 (opens in a new tab)
- crates.io/crates/tuftool/0.15.0 (opens in a new tab)
- github.com/awslabs/tough (opens in a new tab)
- github.com/awslabs/tough/releases/tag/tough-v0.22.0 (opens in a new tab)
- github.com/awslabs/tough/releases/tag/tuftool-v0.15.0 (opens in a new tab)