CVE-2026-95666

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreHIGH confidence

Score 4.3 from GitHub Security Advisory published 2026-09-22. a secondary CVSS source baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0

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

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST /api/v4/posts/ids/reactions}}.. Mattermost Advisory ID: MMSA-2026-00771

CVSS v3
4.3
EG Score
4.3(high)
EG Risk
19(Track)
EG Risk 19/100SSVC: 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
Severity43% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
27%
KEV
Not listed

Published

September 22, 2026

Last Modified

September 22, 2026

Advisory Details (1)

Auto-updated Sep 22, 2026
No patch confirmed yet.
generic

Security Updates | Mattermost Documentation

https://mattermost.com/security-updates

Vendor Advisories for CVE-2026-95666(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 12× in last 7d / 12× 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. 2026-09-24 23:57 UTCEG score recompute
  2. 2026-09-24 23:57 UTCGHSA enrichment
  3. 2026-09-24 14:04 UTCEPSS rescore
  4. 2026-09-23 21:51 UTCEG score recompute
  5. 2026-09-23 21:51 UTCGHSA enrichment
  6. 2026-09-23 17:54 UTCEPSS rescore
  7. 2026-09-22 19:52 UTCEG score recompute
  8. 2026-09-22 19:52 UTCGHSA enrichment
  9. 2026-09-22 14:20 UTCEG score recompute
  10. 2026-09-22 14:06 UTCEG score recompute
  11. 2026-09-22 13:27 UTCEG score recompute
  12. 2026-09-22 13:25 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-95666?
CVE-2026-95666 is a medium vulnerability published on September 22, 2026. Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to limit the length of the post ID array accepted by the bulk reactions endpoint which allows an authenticated user to cause excessive database load via a crafted request to {{POST…
When was CVE-2026-95666 disclosed?
CVE-2026-95666 was first published in the National Vulnerability Database on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-95666 actively exploited?
CVE-2026-95666 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 73.1% of all scored CVEs.
What is the CVSS score of CVE-2026-95666?
CVE-2026-95666 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-95666?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-95666, 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

Explore the affected products and dependency analysis for CVE-2026-95666

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