CVE-2026-39855: osslsigncode is a tool that implements Authenticode signing and timestamping

Q: How do I fix CVE-2026-39855?

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

Q: Is CVE-2026-39855 being exploited?

CVE-2026-39855 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-2026-39855 affect?

CVE-2026-39855 affects osslsigncode. Severity is medium (CVSS 5.5). osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When

Q: How urgent is CVE-2026-39855?

Priority 20/100. No elevated risk signals yet.

Routine

MEDIUM 5.5UPGRADE

CVE-2026-39855 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 integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When page hash processing is performed on a PE file, the function subtracts hdrsize from pagesize without first validating that pagesize >= hdrsize. If a malicious PE file sets SizeOfHeaders (hdrsize) larger than S

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, CWE-190, CWE-191
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-2026-39855?

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

Is CVE-2026-39855 being exploited?

CVE-2026-39855 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-2026-39855 affect?

CVE-2026-39855 affects osslsigncode. Severity is medium (CVSS 5.5). osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When

How urgent is CVE-2026-39855?

Priority 20/100. No elevated risk signals yet.

Related CVEs

CVE-2026-39856 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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