How severe is CVE-2020-15093?

CVE-2020-15093 has a CVSS score of 8.6/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-15093?

CVE-2020-15093 affects the following packages: tough (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2020-15093?

Update tough to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15093 is resolved across your whole dependency graph.

How do I detect CVE-2020-15093 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tough, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-15093 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2020-15093 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-15093 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-15093?

CVE-2020-15093 has an EPSS (Exploit Prediction Scoring System) score of 1.4%, placing it in the 71th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-15093?

CVE-2020-15093 is classified as CWE-347 (CWE-347). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-15093 published, and has it been updated?

CVE-2020-15093 was published on July 9, 2020 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io

Not in CISA KEV

HIGH severity

CVE-2020-15093 — tough

HIGHFix: theupdateframework/tuf@2977188

CVE-2020-15093 is a high-severity (CVSS 8.6) CWE-347 vulnerability in tough. A fix is available for tough — see the affected versions and patch details below.

Improper verification of signature threshold in tough

Also known asGHSA-5q2r-92f9-4m49RUSTSEC-2020-0024

Published

Jul 9, 2020

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs71th percentile — riskier than 71% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-15093 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🦀tough

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

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 [email protected].

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`tough`	all versions	0.7.1`cargo update -p tough --precise 0.7.1`

Affected Products

1 product · 1 configurations

Application

toughamazon

< 0.7.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tough, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tough to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15093 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

## 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