CVE-2026-6966

Name: CVE-2026-6966
Creator: NVD / NIST
Published: 2026-04-24T20:16:28.883+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.26%

Last modified Jun 17, 2026

CVE-2026-6966 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

6.5/10

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

CVSS 4.0

7/10

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.26%

17.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-347

Affected Software

Vendor	Product	Versions
Amazon	Tough	< 0.22.0
Amazon	Tuftool	< 0.15.0

References

https://aws.amazon.com/security/security-bulletins/2026-019-aws/Vendor Advisory
https://crates.io/crates/tough/0.22.0Product
https://crates.io/crates/tuftool/0.15.0Product
https://github.com/awslabs/tough/releases/tag/tough-v0.22.0Release Notes
https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0Release Notes
https://github.com/awslabs/tough/security/advisories/GHSA-8m7c-8m39-rv4xVendor Advisory

Timeline

Published: Apr 24, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-6966?

How severe is CVE-2026-6966?

CVE-2026-6966 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.

How do I fix CVE-2026-6966?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST