CVE-2026-39856: osslsigncode is a tool that implements Authenticode signing and timestamping

Q: How do I fix CVE-2026-39856?

osslsigncode: upgrade to 2.13. Exact commands for each OS are on this page.

Q: Is CVE-2026-39856 being exploited?

CVE-2026-39856 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-39856 affect?

CVE-2026-39856 affects osslsigncode. Severity is medium (CVSS 5.5). 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()). Whe

Q: How urgent is CVE-2026-39856?

Priority 20/100. No elevated risk signals yet.

Routine

MEDIUM 5.5UPGRADE

CVE-2026-39856 is a medium-severity flaw (CVSS 5.5) affecting osslsigncode. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.1% (top 96%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-04-09
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: osslsigncode project

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 17:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

osslsigncode project osslsigncode UPGRADE

Affected: < 2.13

Fixed in: 2.13

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy osslsigncode || rpm -q osslsigncode || osslsigncode --version

2. UPGRADE to 2.13 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade osslsigncode

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade osslsigncode

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39856?

osslsigncode: upgrade to 2.13. Exact commands for each OS are on this page.

Is CVE-2026-39856 being exploited?

CVE-2026-39856 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39856 affect?

CVE-2026-39856 affects osslsigncode. Severity is medium (CVSS 5.5). 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()). Whe

How urgent is CVE-2026-39856?

Priority 20/100. No elevated risk signals yet.

Related CVEs

CVE-2026-39855 MEDIUM 5.5 UPGRADE osslsigncode is a tool that implements Authenticode signing and timestamping
CVE-2026-39853 HIGH 7.8 UPGRADE osslsigncode is a tool that implements Authenticode signing and timestamping

References

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