# CVE-2023-39969: uthenticode signature validation bypass vulnerability

> Attackers can modify binary code without invalidating the Authenticode signature due to incorrect hashing logic in the uthenticode library.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Aug 2023
- **Updated:** 3 Oct 2024
- **Also known as:** GHSA-rc7g-99x7-4p9g

## What is CVE-2023-39969?

CVE-2023-39969 is a critical vulnerability in trailofbits uthenticode, published on 9 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

uthenticode is a small cross-platform library for partially verifying Authenticode digital signatures. Version 1.0.9 of uthenticode hashed the entire file rather than hashing sections by virtual address, in violation of the Authenticode specification. As a result, an attacker could modify code within a binary without changing its Authenticode hash, making it appear valid from uthenticode's perspective. Versions of uthenticode prior to 1.0.9 are not vulnerable to this attack, nor are versions in the 2.x series. By design, uthenticode does not perform full-chain validation. However, the malleability of signature verification introduced in 1.0.9 was an unintended oversight. The 2.x series addresses the vulnerability. Versions prior to 1.0.9 are also not vulnerable, but users are encouraged to upgrade rather than downgrade. There are no workarounds to this vulnerability.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2023-39969?

It affects 1 product.


Products: Trailofbits Uthenticode.

## How do I fix CVE-2023-39969?

No fix has been published for CVE-2023-39969 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-39969 being exploited?

There is no known exploitation of CVE-2023-39969 in the wild and no public exploit code.

## Other vulnerabilities in trailofbits uthenticode

- [CVE-2023-40012](https://insights.sbomify.com/CVE-2023-40012/): uthenticode EKU validation bypass (medium 5.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-39969 and fix it if it is affected.

What it is: CVE-2023-39969 is a critical vulnerability in trailofbits uthenticode, published on 9 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-39969 in the wild and no public exploit code.

Affected product: trailofbits uthenticode. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-39969/ (Markdown: https://insights.sbomify.com/CVE-2023-39969/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39969
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39969
- OSV: https://osv.dev/vulnerability/CVE-2023-39969

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39969/
Summaries are generated and may contain mistakes; the official description above is the record.