CVE-2026-12985

CRITICALNVD 9.39.3
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 0.3% (18th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 6.8 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-09-14) is not newer than that change (2026-10-07), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 3 sources updated this week

Also known asEUVD-2026-77520 (ENISA EUVD) · GHSA-c92j-r2f4-67xg (GitHub Security Advisories)Source: ENISA EUVD

9.3EG
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: 0.3%CVSS: 9.3Exploit: None knownExposed services: Not assessed

Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher (from the CVE record's solution, Mattermost, Inc.) — apply it.

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
42
EG Risk 42/100

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)
Severity93% × 45%
Impact severity (EG Severity): CVSS 9.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 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: Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher (from the CVE record's solution, Mattermost, Inc.). Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
18th
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 (9.3): severity, escalated by confirmed exploitation. This CVE's 9.3 is its impact severity (EG Severity), not escalated.

EG Severity
9.3 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). 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, and whom BOD 26-04 binds: 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).

Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher (from the CVE record's solution, Mattermost, Inc.). 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.

The score's inputs: 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

September 14, 2026

Last Modified

October 7, 2026

Advisory Details (1)

Auto-updated Oct 8, 2026
Fix named in the CVE record's solution (Mattermost, Inc.).
Web page

Security Updates | Mattermost Documentation

https://mattermost.com/security-updates

Vendor Advisories for CVE-2026-12985(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 109× 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 100 of 165 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. None are among the latest 100 rows. The 65 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  2. 2026-11-01 22:04 UTCEG score recompute
  3. 2026-11-01 22:04 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub severity MODERATE · GitHub CVSS 6.8
  4. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  5. 2026-10-31 21:20 UTCEG score recompute
  6. 2026-10-31 21:20 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  7. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  8. 2026-10-30 20:38 UTCEG score recompute
  9. 2026-10-30 20:38 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  10. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  11. 2026-10-29 19:56 UTCEG score recompute
  12. 2026-10-29 19:56 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  13. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  14. 2026-10-28 19:14 UTCEG score recompute
  15. 2026-10-28 19:14 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  16. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  17. 2026-10-27 18:28 UTCEG score recompute
  18. 2026-10-27 18:28 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  19. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  20. 2026-10-26 17:46 UTCEG score recompute
  21. 2026-10-26 17:46 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  22. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  23. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  24. 2026-10-25 16:32 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  25. 2026-10-25 14:49 UTCEG score recompute
Show 75 more
  1. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  2. 2026-10-24 15:48 UTCEG score recompute
  3. 2026-10-24 15:48 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  4. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  5. 2026-10-23 15:04 UTCEG score recompute
  6. 2026-10-23 15:04 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  7. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  8. 2026-10-22 14:19 UTCEG score recompute
  9. 2026-10-22 14:19 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  10. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  11. 2026-10-21 13:35 UTCEG score recompute
  12. 2026-10-21 13:35 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  13. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  14. 2026-10-20 12:53 UTCEG score recompute
  15. 2026-10-20 12:53 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  16. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  17. 2026-10-19 12:09 UTCEG score recompute
  18. 2026-10-19 12:08 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  19. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  20. 2026-10-18 10:19 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  21. 2026-10-18 05:03 UTCEG score recompute
  22. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  23. 2026-10-17 08:45 UTCEG score recompute
  24. 2026-10-17 08:45 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  25. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  26. 2026-10-16 08:02 UTCEG score recompute
  27. 2026-10-16 08:01 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  28. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  29. 2026-10-15 07:03 UTCEG score recompute
  30. 2026-10-15 07:03 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  31. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  32. 2026-10-14 02:53 UTCEG score recompute
  33. 2026-10-14 02:53 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  34. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  35. 2026-10-12 22:59 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  36. 2026-10-12 16:36 UTCEG score recompute
  37. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  38. 2026-10-11 23:28 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  39. 2026-10-11 19:45 UTCEG score recompute
  40. 2026-10-11 19:45 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  41. 2026-10-11 18:24 UTCEG score recompute
  42. 2026-10-11 14:17 UTCEG score recompute
  43. 2026-10-11 14:17 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  44. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  45. 2026-10-11 10:02 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  46. 2026-10-11 06:09 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  47. 2026-10-10 22:59 UTCEG score recompute
  48. 2026-10-10 22:59 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  49. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  50. 2026-10-10 18:11 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  51. 2026-10-10 14:28 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  52. 2026-10-10 10:45 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  53. 2026-10-10 07:02 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  54. 2026-10-10 03:20 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  55. 2026-10-09 23:37 UTCEG score recompute
  56. 2026-10-09 23:37 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  57. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  58. 2026-10-09 19:53 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  59. 2026-10-09 16:12 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  60. 2026-10-09 06:19 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  61. 2026-10-09 02:37 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  62. 2026-10-08 22:56 UTCEG score recompute
  63. 2026-10-08 22:55 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  64. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  65. 2026-10-08 09:30 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  66. 2026-10-08 05:48 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  67. 2026-10-08 02:06 UTCEG score recompute
  68. 2026-10-08 02:05 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  69. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  70. 2026-10-07 22:23 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  71. 2026-10-07 18:18 UTCEG score recompute▲ 2.50
  72. 2026-10-07 18:18 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8
  73. 2026-10-07 18:16 UTCNVD updateCVSS v3 → 9.3 · severity → CRITICAL
  74. 2026-10-07 10:59 UTCEG score recompute
  75. 2026-10-07 10:59 UTCGHSA enrichmentGHSA-c92j-r2f4-67xg · GitHub CVSS 6.8

Frequently asked(5)

What is CVE-2026-12985?
CVE-2026-12985 is a critical-severity vulnerability; its CVE record was published on September 14, 2026. Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client…
When was the CVE record for CVE-2026-12985 published?
The CVE record for CVE-2026-12985 was published on September 14, 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 7, 2026; the record at its source may have been updated since.
Is CVE-2026-12985 actively exploited?
CVE-2026-12985 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (18th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-12985?
CVE-2026-12985 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-12985?
The CVE record's solution for CVE-2026-12985, written by its CNA Mattermost, Inc., names the fix: "Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher." The vendor advisories EchelonGraph has for CVE-2026-12985 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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