Which versions of AWS tough are affected by CVE-2026-6967?

CVE-2026-6967 affects AWS TUF (The Update Framework) client library versions before 0.22.0, allowing authenticated users with delegated signing privileges to inject invalid metadata into local caches…. A patch is available.

How to fix or mitigate CVE-2026-6967?

Within 24 hours: Identify all systems and CI/CD pipelines using AWS tough library-check dependency manifests for tough-rs versions <0.22.0. Within 7 days: Upgrade tough to v0.22.0 or later and tuftool to v0.15.0 or later; validate upgrades in non-production environments. Within 30 days: Audit delegated signer certificates and revoke any with suspicious modification timestamps; conduct metadata cache integrity reviews on affected systems deployed in the past 90 days.

AWS tough CVE-2026-6967

Q: What is the CVSS score of CVE-2026-6967?

CVE-2026-6967 has a CVSS 4.0 base score of 7.1 (High). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:L/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 exploitation probability: 0.0%.

EUVD-2026-25628 HIGH

Insufficient Verification of Data Authenticity (CWE-345)

2026-04-24 AMZN

GHSA-4v58-8p28-2rq3

Authentication Bypass Tough Tuftool

7.1

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

7.1 HIGH

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:L/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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:L/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

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Re-analysis Queued

Apr 24, 2026 - 21:22 vuln.today

cvss_changed

Analysis Generated

Apr 24, 2026 - 20:32 vuln.today

Severity Changed

Apr 24, 2026 - 20:22 NVD

MEDIUM HIGH

CVSS changed

Apr 24, 2026 - 20:22 NVD

5.9 (MEDIUM) 7.1 (HIGH)

EUVD ID Assigned

Apr 24, 2026 - 20:15 euvd

EUVD-2026-25628

Analysis Generated

Apr 24, 2026 - 20:15 vuln.today

Patch released

Apr 24, 2026 - 20:15 nvd

Patch available

CVE Published

Apr 24, 2026 - 19:41 nvd

HIGH 7.1

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

3 cargo packages depend on tough (3 direct, 0 indirect)

Ecosystem-wide dependent count for version 0.9.0.

DescriptionCVE.org

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.

We recommend you upgrade to tough-v0.22.0 / tuftool-v0.15.0.

AnalysisAI

Metadata integrity bypass in AWS tough (TUF client library) before v0.22.0 allows authenticated users with delegated signing authority to poison local metadata caches by bypassing expiration, hash, and length validation checks. The vulnerability exists because load_delegations skips specification-mandated integrity checks applied to top-level targets metadata, enabling malicious delegated signers to inject invalid metadata. AWS has released patches in tough-v0.22.0 and tuftool-v0.15.0. CVSS 7.1 reflects network vector but high attack complexity (AT:P indicates specialized conditions). No public exploit or active exploitation confirmed at time of analysis, though authentication bypass tag suggests significant trust boundary violation.

Technical ContextAI

The Update Framework (TUF) is a framework for securing software update systems, used by AWS for package distribution and artifact signing. Tough is AWS Labs' Rust implementation of a TUF client library (cpe:2.3:a:aws:tough). TUF relies on a delegation chain where top-level metadata signs delegated targets metadata, with each layer subject to integrity checks including signature verification, expiration timestamps, content hashes, and length constraints per the specification. This vulnerability (CWE-345: Insufficient Verification of Data Authenticity) occurs in the load_delegations function, which processes delegated targets metadata but fails to enforce the same validation rules applied to top-level metadata. The missing checks allow delegated signers-who possess valid signing keys for their delegation scope-to craft metadata that violates TUF integrity constraints (expired timestamps, mismatched hashes, incorrect lengths) without detection. This breaks the defense-in-depth model where each metadata layer should independently validate its delegated content.

RemediationAI

Upgrade to tough-v0.22.0 or later and tuftool-v0.15.0 or later as recommended by AWS in security bulletin 2026-019-aws. Patched releases available at https://github.com/awslabs/tough/releases/tag/tough-v0.22.0 and https://github.com/awslabs/tough/releases/tag/tuftool-v0.15.0, with crates published to https://crates.io/crates/tough/0.22.0 and https://crates.io/crates/tuftool/0.15.0. Organizations unable to upgrade immediately should audit their TUF delegation chains to ensure all delegated signers are trusted and implement enhanced monitoring for metadata anomalies (expired timestamps, hash mismatches in logs). As a temporary compensating control, consider removing or limiting delegation depth in TUF repositories, which reduces attack surface by eliminating the vulnerable code path entirely, though this may impact operational flexibility for teams relying on delegation for distributed signing workflows. Note that this workaround prevents use of delegated targets metadata feature until patching is completed.