CVE-2023-39969: uthenticode is a small cross-platform library for partially verifying Authenticode digital signatures. Version 1.0.9 of uthenticode hashed the entire ...

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.46%

36.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-347

Affected Software

Vendor	Product	Versions
Trailofbits	Uthenticode	< 1.0.9

References

Timeline

Published: Aug 9, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-39969?

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.

How severe is CVE-2023-39969?

CVE-2023-39969 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.46% probability of exploitation in the next 30 days.

How do I fix CVE-2023-39969?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.