CVE-2026-39856

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 can craft a PE file with section headers that point beyond the end of the file. When osslsigncode computes page hashes for such a file, it may attempt to hash data from an invalid memory region, causing an out-of-bounds read and potentially crashing the process. The vulnerability can be triggered while signing a malicious PE file with page hashing enabled (-ph), or while verifying a malicious signed PE file that already contains page hashes. Verification of an already signed file does not require the verifier to pass -ph. This vulnerability is fixed in 2.13.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

April 9, 2026

Last Modified

April 17, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
Patch available. Sources: github_commit, github_release, github.
github Patch Available

Out-of-Bounds Read via Unvalidated Section Bounds in PE Page Hash Calculation · Advisory · mtrojnar/osslsigncode · GitHub

Affected: version 2.13:

https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-rjrx-chvw-8jw8
github_release Patch Available

2.13

Patch available: mtrojnar/osslsigncode 2.13

https://github.com/mtrojnar/osslsigncode/releases/tag/2.13
github_commit Patch Available

commit 92f8761b4770 (mtrojnar/osslsigncode)

Patch available: mtrojnar/osslsigncode 2.13 (contains commit 92f8761b4770)

https://github.com/mtrojnar/osslsigncode/commit/92f8761b4770f76a36731969b5040ce3b9a09570

Vendor Advisories for CVE-2026-39856(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
osslsigncode2.1-1 ... 2.9-2 (21 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
osslsigncode2.10-1 ... 2.9-2 (12 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
osslsigncode2.10-1 ... 2.9-2 (7 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
osslsigncode2.10-1, 2.11-1, 2.12-1, 2.9-22.13-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 150 total refreshes for this CVE.

  1. 2026-09-15 03:11 UTCEPSS rescore
  2. 2026-09-13 16:47 UTCEPSS rescore
  3. 2026-09-12 15:01 UTCEPSS rescore
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  12. 2026-09-02 07:44 UTCOSV refresh
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  1. 2026-08-16 14:56 UTCEPSS rescore
  2. 2026-08-16 07:13 UTCEG score recompute
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  5. 2026-08-14 05:09 UTCEG score recompute
  6. 2026-08-13 22:00 UTCEPSS rescore
  7. 2026-08-12 19:25 UTCEG score recompute
  8. 2026-08-12 13:51 UTCEPSS rescore
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  10. 2026-08-11 04:18 UTCEG score recompute
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  23. 2026-08-02 13:56 UTCEG score recompute
  24. 2026-08-02 02:27 UTCEPSS rescore
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  26. 2026-07-30 16:28 UTCEPSS rescore
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  37. 2026-07-23 03:10 UTCEG score recompute
  38. 2026-07-22 14:08 UTCEPSS rescore
  39. 2026-07-21 15:24 UTCEPSS rescore
  40. 2026-07-20 20:32 UTCOSV refresh
  41. 2026-07-20 17:08 UTCEPSS rescore
  42. 2026-07-19 14:31 UTCEPSS rescore
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  44. 2026-07-16 17:03 UTCEPSS rescore
  45. 2026-07-15 16:57 UTCEPSS rescore
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  51. 2026-07-12 05:46 UTCEPSS rescore
  52. 2026-07-11 08:27 UTCEPSS rescore
  53. 2026-07-09 19:10 UTCEPSS rescore
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  74. 2026-06-21 14:56 UTCEPSS rescore
  75. 2026-06-21 14:56 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-39856?
CVE-2026-39856 is a medium vulnerability published on April 9, 2026. 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 (pepagehash_calc()). When processing PE sections for page hashing, the function uses…
When was CVE-2026-39856 disclosed?
CVE-2026-39856 was first published in the National Vulnerability Database on April 9, 2026, with the most recent update on April 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39856 actively exploited?
CVE-2026-39856 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 96.1% of all scored CVEs.
What is the CVSS score of CVE-2026-39856?
CVE-2026-39856 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-39856?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39856, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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