Vulnerability Description
osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. During verification of a PKCS#7 signature, the code copies the digest value from a parsed SpcIndirectDataContent structure into a fixed-size stack buffer (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) without validating that the source length fits within the destination buffer. This pattern is present in the verification handlers for PE, MSI, CAB, and script files. An attacker can craft a malicious signed file with an oversized digest field in SpcIndirectDataContent. When a user verifies such a file with osslsigncode verify, the unbounded memcpy can overflow the stack buffer and corrupt adjacent stack state. This vulnerability is fixed in 2.12.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Osslsigncode Project | Osslsigncode | < 2.12 |
Related Weaknesses (CWE)
References
- https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943edPatch
- https://github.com/mtrojnar/osslsigncode/releases/tag/2.12ProductRelease Notes
- https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4Vendor Advisory
FAQ
What is CVE-2026-39853?
CVE-2026-39853 is a vulnerability with a CVSS score of 7.8 (HIGH). osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. Durin...
How severe is CVE-2026-39853?
CVE-2026-39853 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-39853?
Check the references section above for vendor advisories and patch information. Affected products include: Osslsigncode Project Osslsigncode.