CVE-2026-39856: osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an out-of-bounds read…
CVE-2026-39856 · Severity: medium · CVSS 5.5 · Published 2026-04-09
osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an out-of-bounds read vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When processing PE sections for page hashing, the function uses PointerToRawData and SizeOfRawData values from section headers without validating that the referenced region lies within the mapped file. An attacker can craft a PE file with section headers that point beyond the end of the file. When osslsigncode computes page hashes for such a file, it may attempt to hash data from an invalid memory region, causing an out-of-bounds read and potentially crashing 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.
No. Junglewise Threat Intelligence has no report of CVE-2026-39856 being exploited in the wild.
How severe is CVE-2026-39856?
Medium severity, with a CVSS score of 5.5, published 9 April 2026.
Which products and versions are affected?
Osslsigncode Project Osslsigncode. The advisory does not name versions.
Is there a fix for CVE-2026-39856?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-39856?
Check whether you run Osslsigncode Project Osslsigncode. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.