CVE-2026-39855

osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When page hash processing is performed on a PE file, the function subtracts hdrsize from pagesize without first validating that pagesize >= hdrsize. If a malicious PE file sets SizeOfHeaders (hdrsize) larger than SectionAlignment (pagesize), the subtraction underflows and produces a very large unsigned length. The code allocates a zero-filled buffer of pagesize bytes and then attempts to hash pagesize - hdrsize bytes from that buffer. After the underflow, this results in an out-of-bounds read from the heap and can crash the process. The vulnerability can be triggered while signing a malicious PE file with page hashing enabled (-ph), or while verifying a malicious signed PE file that already contains page hashes. Verification of an already signed file does not require the verifier to pass -ph. This vulnerability is fixed in 2.13.

CVSS v3 5.5 MEDIUM

5.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/mtrojnar/osslsigncode/commit/2a5409b7c4b6c6fad2b093531e8fea6cf08e1568	Patch
https://github.com/mtrojnar/osslsigncode/releases/tag/2.13	Product Release Notes
https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-76vv-x5rr-q3mr	Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:osslsigncode_project:osslsigncode:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-04-09 17:16

Updated : 2026-06-17 10:42

NVD link : CVE-2026-39855

Mitre link : CVE-2026-39855

CVE.ORG link : CVE-2026-39855

JSON object : View

Products Affected

osslsigncode_project

osslsigncode

CWE

CWE-125

Out-of-bounds Read

CWE-190

Integer Overflow or Wraparound

CWE-191

Integer Underflow (Wrap or Wraparound)

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