CVE-2025-9076

mediumpriority · track · 26OT risk · elevatedEPSS 0.003 · 17 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.26% (17th) EPSS

CVSS 6.5 · medium

Is it mine?

25 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · osv · cert_bund

EPSS · scored 2026-10-23

Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.

cvss

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 3.6

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · ENISA EU

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 1.2 · impact 5.2

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · OSV

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-862USCWE-862US

affected products (25)

Products and version ranges known to be affected.

Mattermost Mattermost Servr <10.10.2all versionscert_bundDE
Mattermost Mattermost Servr <10.11.0all versionscert_bundDE
Mattermost Mattermost Servr <10.5.10all versionscert_bundDE
Mattermost Mattermost Servr <10.5.9all versionscert_bundDE
Mattermost Mattermost Servr <10.8.4all versionscert_bundDE
Mattermost Mattermost Servr <10.9.4all versionscert_bundDE
Mattermost Mattermost Servr <10.9.5all versionscert_bundDE
Mattermost Mattermost Servr <9.11.18all versionscert_bundDE
Mattermost Mattermost≤ Servr <10.8.4cert_bundDE
Mattermost Mattermost≤ Servr <10.10.2cert_bundDE
Mattermost Mattermost≤ Servr <10.11.0cert_bundDE
Mattermost Mattermost≤ Servr <10.5.10cert_bundDE
Mattermost Mattermost≤ Servr <10.5.9cert_bundDE
Mattermost Mattermost≤ Servr <10.9.4cert_bundDE
Mattermost Mattermost≤ Servr <10.9.5cert_bundDE
Mattermost Mattermost≤ Servr <9.11.18cert_bundDE
Mattermost Mattermost≤ 10.10.0 ≤10.10.1enisa_euvdEU
Mattermost Mattermostall versionsenisa_euvdEU
mattermost mattermost server10.10.0 → 10.10.2nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Go github.com/mattermost/mattermost-server10.10.0 → 10.10.2osvUSpkg:golang/github.com/mattermost/mattermost-server

showing 20 of 25

advisories (3)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2025-1856Mattermost Server: Mehrere SchwachstellenDeutsch2025-08-17csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Mattermost Server ausnutzen, um Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen oder Code auszuführen.
GHSA-3vcm-c42p-3hhfMattermost Missing Authorization vulnerability2025-09-15ghsa · osvUS
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.
GO-2025-3950Mattermost Missing Authorization vulnerability in github.com/mattermost/mattermost-server2025-09-17vendor · osvUS
Mattermost Missing Authorization vulnerability in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/mattermost/mattermost/server/v8 before v8.0.0-20250729073403-517ae758cd02.

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv cert_bund nvd NVD CVE.org MITRE

published 2025-09-15modified 2026-10-19

references (4)

External citations — patches, advisories, analysis.

scry

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