CVE-2026-39855 (GCVE-0-2026-39855)

Vulnerability from cvelistv5 – Published: 2026-04-09 15:58 – Updated: 2026-04-09 19:22
VLAI
Title
osslsigncode has an Integer Underflow in PE Page Hash Calculation Can Cause Out-of-Bounds Read
Summary
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.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-04-09 19:12 UTC
CWE
  • CWE-125 - Out-of-bounds Read
  • CWE-190 - Integer Overflow or Wraparound
  • CWE-191 - Integer Underflow (Wrap or Wraparound)
Assigner
GitHub_M CNA
References
Impacted products
Vendor Product Version
mtrojnar osslsigncode Affected: < 2.13
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