What’s Vulnerable › Vulnerabilities

CVE-2026-6966: Signature Threshold Bypass in awslabs/tough Delegated Roles

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-24 · updated 2026-10-26
• Weakness: CWE-347

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.

Affected products

• AWS tough: before 0.22.0 — fixed in 0.22.0
• AWS tuftool: before 0.15.0 — fixed in 0.15.0

How to fix

Upgrade to a fixed version: AWS tough 0.22.0; AWS tuftool 0.15.0. Check the vendor advisory for mitigations.

References

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

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