CVE-2026-4265

mediumpriority · track · 0OT risk · elevatedEPSS 0.002 · 13 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.23% (13th) EPSS

CVSS 4.3 · medium

Is it mine?

28 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-27

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553

cvss

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

4.3

010

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

v3.14.3mediumAV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · FSTEC (BDU) RU

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · ENISA EU

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 2.8 · impact 1.4

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · OSV

v3.14mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

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

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-863USCWE-863USCWE-863US

affected products (28)

Products and version ranges known to be affected.

Mattermost Mattermost Server <10.11.11all versionscert_bundDE
Mattermost Mattermost Server <11.2.3all versionscert_bundDE
Mattermost Mattermost Server <11.3.1all versionscert_bundDE
Mattermost Mattermost Server <11.4.0all versionscert_bundDE
Mattermost Mattermost≤ Server <11.2.3cert_bundDE
Mattermost Mattermost≤ Server <10.11.11cert_bundDE
Mattermost Mattermost≤ Server <11.3.1cert_bundDE
Mattermost Mattermost≤ Server <11.4.0cert_bundDE
Mattermost Mattermost≤ 11.2.0 ≤11.2.2enisa_euvdEU
Mattermost Mattermost≤ 10.11.0 ≤10.11.10enisa_euvdEU
Mattermost Mattermost≤ 11.3.0 ≤11.3.0enisa_euvdEU
Mattermost Inc Mattermost≤ 10.11.11fstec_bduRU
Mattermost Inc Mattermost≤ 11.2.3fstec_bduRU
Mattermost Inc Mattermost≤ 11.3.1fstec_bduRU
Mattermost Inc Mattermost≤ 11.4.0fstec_bduRU
mattermost mattermost server10.11.0 → 10.11.11nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.2.0 → 11.2.3nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.3.0 → 11.3.1nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Go github.com/mattermost/mattermost-server< 5.3.2-0.20260107144005-c7f6efdfb035osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server10.11.0-rc1 → 10.11.11osvUSpkg:golang/github.com/mattermost/mattermost-server

showing 20 of 28

advisories (3)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-0745Mattermost: Mehrere SchwachstellenDeutsch2026-03-16csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Mattermost ausnutzen, um Sicherheitsvorkehrungen zu umgehen, und um nicht näher spezifizierte Auswirkungen zu verursachen.
GHSA-xpvf-6qcc-9jqcMattermost fails to validate team-specific upload_file permissions2026-03-16ghsa · osvUS
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553
GO-2026-4749Mattermost fails to validate team-specific upload_file permissions in github.com/mattermost/mattermost-server2026-03-23vendor · osvUS
Mattermost fails to validate team-specific upload_file permissions 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/v5 before v5.3.2-0.20260107144005-c7f6efdfb035.

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu osv cert_bund nvd NVD CVE.org MITRE

published 2026-03-16modified 2026-06-17

references (3)

External citations — patches, advisories, analysis.

scry

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