CVE-2026-6966
Signature Threshold Bypass in awslabs/tough Delegated Roles
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.
INFO
Published Date :
April 24, 2026, 8:16 p.m.
Last Modified :
May 6, 2026, 3:24 p.m.
Remotely Exploit :
Yes !
Source :
ff89ba41-3aa1-4d27-914a-91399e9639e5
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | ff89ba41-3aa1-4d27-914a-91399e9639e5 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | HIGH | ff89ba41-3aa1-4d27-914a-91399e9639e5 | ||||
| CVSS 4.0 | HIGH | ff89ba41-3aa1-4d27-914a-91399e9639e5 |
Solution
- Upgrade the application to tough-v0.22.0 or later.
- Update tuftool to v0.15.0 or later.
Public PoC/Exploit Available at Github
CVE-2026-6966 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6966.
| URL | Resource |
|---|---|
| https://aws.amazon.com/security/security-bulletins/2026-019-aws/ | Vendor Advisory |
| https://crates.io/crates/tough/0.22.0 | Product |
| https://crates.io/crates/tuftool/0.15.0 | Product |
| https://github.com/awslabs/tough/releases/tag/tough-v0.22.0 | Release Notes |
| https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0 | Release Notes |
| https://github.com/awslabs/tough/security/advisories/GHSA-8m7c-8m39-rv4x | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6966 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6966
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6966 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6966 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 06, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:amazon:tough:*:*:*:*:*:rust:*:* versions up to (excluding) 0.22.0 *cpe:2.3:a:amazon:tuftool:*:*:*:*:*:rust:*:* versions up to (excluding) 0.15.0 Added Reference Type AMZN: https://aws.amazon.com/security/security-bulletins/2026-019-aws/ Types: Vendor Advisory Added Reference Type AMZN: https://crates.io/crates/tough/0.22.0 Types: Product Added Reference Type AMZN: https://crates.io/crates/tuftool/0.15.0 Types: Product Added Reference Type AMZN: https://github.com/awslabs/tough/releases/tag/tough-v0.22.0 Types: Release Notes Added Reference Type AMZN: https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0 Types: Release Notes Added Reference Type AMZN: https://github.com/awslabs/tough/security/advisories/GHSA-8m7c-8m39-rv4x Types: Vendor Advisory -
CVE Modified by ff89ba41-3aa1-4d27-914a-91399e9639e5
Apr. 24, 2026
Action Type Old Value New Value Added Reference https://github.com/awslabs/tough/security/advisories/GHSA-8m7c-8m39-rv4x -
New CVE Received by ff89ba41-3aa1-4d27-914a-91399e9639e5
Apr. 24, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N Added CWE CWE-347 Added Reference https://aws.amazon.com/security/security-bulletins/2026-019-aws/ Added Reference https://crates.io/crates/tough/0.22.0 Added Reference https://crates.io/crates/tuftool/0.15.0 Added Reference https://github.com/awslabs/tough/releases/tag/tough-v0.22.0 Added Reference https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0