# CVE-2026-39853: osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow…

Source: https://junglewise.ai/threats/cve-2026-39853-osslsigncode-is-a-tool-that-implements-authenticode-signing-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-09  
License: CC BY 4.0 with a link back

CVE-2026-39853 · Severity: high · CVSS 7.8 · Published 2026-04-09

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.

Technologies: [Osslsigncode Project Osslsigncode](https://junglewise.ai/threats/technologies/osslsigncode). Vendors: [Osslsigncode Project](https://junglewise.ai/threats/vendors/osslsigncode-project).

## Quick answers

**Is CVE-2026-39853 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39853 being exploited in the wild.

**How severe is CVE-2026-39853?** High severity, with a CVSS score of 7.8, 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-2026-39853?** 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-2026-39853?** 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.

## Affected products

- Osslsigncode Project Osslsigncode

## Related threats

- [osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an out-of-bounds read…](https://junglewise.ai/threats/cve-2026-39856-osslsigncode-is-a-tool-that-implements-authenticode-signing-and)
- [osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow…](https://junglewise.ai/threats/cve-2026-39855-osslsigncode-is-a-tool-that-implements-authenticode-signing-and)