CVE-2026-39853

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.8 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 94% 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
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: 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 2.12, 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.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

April 9, 2026

Last Modified

April 17, 2026

Advisory Details (3)

Auto-updated Jun 11, 2026
Patch available. Sources: github_commit, github_release, github.
github Patch Available

Stack Buffer Overflow via Unbounded Digest Copy During Signature Verification · Advisory · mtrojnar/osslsigncode · GitHub

Affected: version 2.12:

https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4
github_release Patch Available

2.12

Patch available: mtrojnar/osslsigncode 2.12

https://github.com/mtrojnar/osslsigncode/releases/tag/2.12
github_commit Patch Available

commit cbee1e723c5a (mtrojnar/osslsigncode)

Patch available: mtrojnar/osslsigncode 2.12 (contains commit cbee1e723c5a)

https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68

Vendor Advisories for CVE-2026-39853(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 38× 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.

  1. 2026-07-27 14:13 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
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  8. 2026-07-23 14:18 UTCEPSS rescore
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  10. 2026-07-23 03:10 UTCEG score recompute
  11. 2026-07-22 14:08 UTCEPSS rescore
  12. 2026-07-21 15:24 UTCEPSS rescore
  13. 2026-07-20 20:32 UTCOSV refresh
  14. 2026-07-20 17:08 UTCEPSS rescore
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  1. 2026-07-09 19:10 UTCEPSS rescore
  2. 2026-07-08 15:15 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
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  5. 2026-07-06 02:23 UTCEPSS rescore
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  8. 2026-07-04 06:31 UTCEPSS rescore
  9. 2026-07-01 15:06 UTCEPSS rescore
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-29 14:06 UTCEPSS rescore
  12. 2026-06-28 14:07 UTCEPSS rescore
  13. 2026-06-28 04:56 UTCEPSS rescore
  14. 2026-06-27 03:08 UTCEPSS rescore
  15. 2026-06-25 13:49 UTCEPSS rescore
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  17. 2026-06-24 14:05 UTCEPSS rescore
  18. 2026-06-23 21:33 UTCEPSS rescore
  19. 2026-06-22 14:25 UTCEPSS rescore
  20. 2026-06-22 14:25 UTCEPSS rescore
  21. 2026-06-21 14:56 UTCEPSS rescore
  22. 2026-06-21 14:56 UTCEPSS rescore
  23. 2026-06-21 01:59 UTCEPSS rescore
  24. 2026-06-19 19:25 UTCEPSS rescore
  25. 2026-06-18 17:52 UTCEPSS rescore
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  27. 2026-06-17 17:53 UTCEPSS rescore
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  29. 2026-06-15 17:49 UTCEPSS rescore
  30. 2026-06-14 23:18 UTCEPSS rescore
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  32. 2026-06-12 23:12 UTCEPSS rescore
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  35. 2026-06-10 22:18 UTCEPSS rescore
  36. 2026-06-10 13:22 UTCEPSS rescore
  37. 2026-06-08 14:17 UTCEPSS rescore
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  39. 2026-06-07 15:25 UTCEPSS rescore
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  42. 2026-06-06 13:47 UTCEPSS rescore
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  44. 2026-06-05 22:47 UTCEPSS rescore
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  46. 2026-06-05 06:10 UTCEPSS rescore
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  48. 2026-06-04 13:12 UTCEPSS rescore
  49. 2026-06-04 13:12 UTCEPSS rescore
  50. 2026-06-02 20:13 UTCEPSS rescore
  51. 2026-06-01 13:52 UTCEPSS rescore
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  59. 2026-05-29 13:44 UTCEPSS rescore
  60. 2026-05-29 13:44 UTCEPSS rescore
  61. 2026-05-28 13:44 UTCEPSS rescore
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  63. 2026-05-28 13:44 UTCEPSS rescore
  64. 2026-05-27 13:40 UTCEPSS rescore
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  67. 2026-05-26 13:44 UTCEPSS rescore
  68. 2026-05-26 07:18 UTCEPSS rescore
  69. 2026-05-26 07:18 UTCEPSS rescore
  70. 2026-05-20 18:06 UTCEG score recompute
  71. 2026-05-20 11:22 UTCEPSS rescore
  72. 2026-05-20 11:22 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-39853?
CVE-2026-39853 is a high vulnerability published on April 9, 2026. 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…
When was CVE-2026-39853 disclosed?
CVE-2026-39853 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-2026-39853 actively exploited?
CVE-2026-39853 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 94.1% of all scored CVEs.
What is the CVSS score of CVE-2026-39853?
CVE-2026-39853 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-39853?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39853, 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.

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