CVE-2026-39853

HIGHNVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This high-severity CVE scores 7.8 under NVD CVSS v3. EPSS exploit probability: 0.2% (5th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-20942 (ENISA EUVD)Source: ENISA EUVD

7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
5th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 9, 2026

Last Modified

October 26, 2026

Advisory Details (3)

Auto-updated Jun 11, 2026
Patch available. Sources: github_commit, github_release, github.
GitHub advisoryMentions a patch (unverified)

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.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
osslsigncode2.1-1 ... 2.9-2 (21 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
osslsigncode2.10-1 ... 2.9-2 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
osslsigncode2.10-1 ... 2.9-2 (7 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
osslsigncode2.10-1, 2.11-1, 2.9-2
  • every version up to 2.12-1: fixed in 2.12-1
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 39× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 200 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 101 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  2. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  3. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  4. 2026-10-26 21:32 UTCEG score recompute
  5. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  6. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  7. 2026-10-25 14:31 UTCEG score recompute
  8. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  9. 2026-10-23 23:58 UTCEG score recompute
  10. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  13. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  15. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  16. 2026-10-18 03:43 UTCEG score recompute
  17. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-10-17 14:59 UTCEG score recompute
  19. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  20. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  24. 2026-10-12 16:10 UTCEG score recompute
  25. 2026-10-11 19:52 UTCEG score recompute
Show 74 more
  1. 2026-10-11 17:05 UTCEG score recompute
  2. 2026-10-11 14:32 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  4. 2026-10-10 21:33 UTCOSV refresh
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  7. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  8. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  9. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  10. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  11. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  12. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  15. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-09-21 09:19 UTCOSV refresh
  19. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  20. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  21. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  22. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  23. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  24. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  25. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  26. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  27. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  28. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  29. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  30. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  31. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  32. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  33. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  34. 2026-09-02 07:44 UTCOSV refresh
  35. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  36. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  37. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  38. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  39. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  40. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  41. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  42. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  43. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  44. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  45. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  46. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  47. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  48. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  49. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  50. 2026-08-16 07:13 UTCEG score recompute
  51. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  52. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  53. 2026-08-14 05:09 UTCEG score recompute
  54. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  55. 2026-08-12 19:25 UTCEG score recompute
  56. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  57. 2026-08-11 19:29 UTCEG score recompute
  58. 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  59. 2026-08-11 03:02 UTCEG score recompute
  60. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  61. 2026-08-09 17:08 UTCEG score recompute
  62. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  63. 2026-08-09 04:35 UTCEG score recompute
  64. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  65. 2026-08-08 03:04 UTCEG score recompute
  66. 2026-08-07 14:30 UTCEG score recompute
  67. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  68. 2026-08-05 23:46 UTCEG score recompute
  69. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  70. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  71. 2026-08-04 10:38 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  72. 2026-08-03 22:00 UTCEG score recompute
  73. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  74. 2026-08-02 13:56 UTCEG score recompute

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Frequently asked(5)

What is CVE-2026-39853?
CVE-2026-39853 is a high-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-39853 published?
The CVE record for CVE-2026-39853 was published on April 9, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-39853 actively exploited?
CVE-2026-39853 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-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?
A fix for CVE-2026-39853 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-39853 are linked in the Vendor Advisories panel on this page.

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