CVE-2026-6966

Description

Improper verification of cryptographic signature uniqueness in delegated role validation in awslabs/tough before tough-v0.22.0 allows remote authenticated users to bypass the TUF signature threshold requirement by duplicating a valid signature, causing the client to accept forged delegated role metadata. We recommend you upgrade to tough-v0.22.0 / tuftool-v0.15.0.

CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-347 CWE-347

Affected Products

Vendor	Product	Versions
amazon	tough	< 0.22.0
amazon	tuftool	< 0.15.0

References

Advisories & Patches

https://aws.amazon.com/security/security-bulletins/2026-019-aws/ https://github.com/awslabs/tough/security/advisories/GHSA-8m7c-8m39-rv4x

Other References

https://crates.io/crates/tough/0.22.0 https://crates.io/crates/tuftool/0.15.0 https://github.com/awslabs/tough/releases/tag/tough-v0.22.0 https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0

Frequently Asked Questions

What is CVE-2026-6966? +

Improper verification of cryptographic signature uniqueness in delegated role validation in awslabs/tough before tough-v0.22.0 allows remote authenticated users to bypass the TUF signature threshold requirement by duplicating a valid signature, causing the client to accept forged delegated role metadata. We recommend you upgrade to tough-v0.22.0 / tuftool-v0.15.0. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-6966? +

CVE-2026-6966 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-6966? +

CVE-2026-6966 affects products from amazon, specifically: tough, tuftool. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-6966? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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