Improper verification of signature threshold in tough

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2020-15093: 1.36% estimated exploitation activity in the next 30 days; percentile 71.70 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The tough library, prior to 0.7.1, does not properly verify the uniqueness of keys in the signatures provided to meet the threshold of cryptographic signatures. It allows someone with access to a valid signing key to create multiple valid signatures in order to circumvent TUF requiring a minimum threshold of unique keys before the metadata is considered valid. AWS would like to thank Erick Tryzelaar of the Google Fuchsia Team for reporting this issue. Patches A fix is available in version 0.7.1. Workarounds No workarounds to this issue are known. References CVE-2020-6174 is assigned to the same issue in the TUF reference implementation. https://github.com/theupdateframework/tuf/pull/974 https://nvd.nist.gov/vuln/detail/CVE-2020-6174 For more information If you have any questions or comments about this advisory, contact AWS Security at aws-security@amazon.com.

Published by the source

25 Aug 2021, 20:56 UTC

Last modified by the source

3 Feb 2023, 05:05 UTC

Source last checked

26 Oct 2026, 15:33 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5q2r-92f9-4m49

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# Patch Next advisory brief: CVE-2020-15093

Advisory: Improper verification of signature threshold in tough
IDs: CVE-2020-15093, GHSA-5q2r-92f9-4m49
Record: https://patchnext.com/advisories/cve-2020-15093 (revision 1, source checked 26 Oct 2026, 15:33 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tough 0.7.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io tough: affected < 0.7.1; fixed in 0.7.1

## Suggested inspection (read-only)
- crates.io tough: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tough.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5q2r-92f9-4m49 (GitHub-reviewed advisory GHSA-5q2r-92f9-4m49 lists affected ranges: crates.io tough >=0 <0.7.1)

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