What is CVE-2026-39856?

CVE-2026-39856 is a medium-severity vulnerability in Mtrojnar Osslsigncode, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-04-09.

How severe is CVE-2026-39856?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Out-of-bounds Read in Mtrojnar Osslsigncode

CVE-2026-39856

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()). Wh…

Vulnerability class: Buffer Overflow

EPSS: 0.000 (4.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

Affected products

Mtrojnar Osslsigncode — versions < 2.13

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-rjrx-chvw-8jw8 (x_refsource_CONFIRM)
https://github.com/mtrojnar/osslsigncode/commit/92f8761b4770f76a36731969b5040ce3b9a09570 (x_refsource_MISC)
https://github.com/mtrojnar/osslsigncode/releases/tag/2.13 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-39856?: CVE-2026-39856 is a medium-severity vulnerability in Mtrojnar Osslsigncode, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-04-09.
How severe is CVE-2026-39856?: Medium severity. CVSS v3 base score is 5.5 out of 10.