CVE-2026-25783

mediumpriority · track · 0EPSS 0.003 · 22 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.30% (22nd) EPSS

CVSS 4.3 · medium

Is it mine?

36 products

Check your exposure

Who says so?

5 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 properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586

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:L/I:N/A:Nsecondary · FSTEC (BDU) RU

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

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

v3.14mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/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-1287USCWE-1287USCWE-1287US

affected products (36)

Products and version ranges known to be affected.

Mattermost Mattermost Desktop <5.13.3.0all versionscert_bundDE
Mattermost Mattermost Desktop <5.13.4.0all versionscert_bundDE
Mattermost Mattermost Plugins <10.11.11all versionscert_bundDE
Mattermost Mattermost Plugins <2.3.1.0all versionscert_bundDE
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≤ Plugins <2.3.1.0cert_bundDE
Mattermost Mattermost≤ Desktop <5.13.3.0cert_bundDE
Mattermost Mattermost≤ Desktop <5.13.4.0cert_bundDE
Mattermost Mattermost≤ Plugins <10.11.11cert_bundDE
Mattermost Mattermost≤ Server <10.11.11cert_bundDE
Mattermost Mattermost≤ Server <11.2.3cert_bundDE
Mattermost Mattermost≤ Server <11.3.1cert_bundDE
Mattermost Mattermost≤ Server <11.4.0cert_bundDE
Mattermost Mattermost≤ 11.3.0 ≤11.3.0enisa_euvdEU
Mattermost Mattermost≤ 10.11.0 ≤10.11.10enisa_euvdEU
Mattermost Mattermost≤ 11.2.0 ≤11.2.2enisa_euvdEU
Mattermost Inc Mattermost≤ 11.2.3fstec_bduRU

showing 20 of 36

advisories (3)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-0422Mattermost: Mehrere SchwachstellenDeutsch2026-02-15csaf · cert_bundDE
Ein authentisierter Angreifer kann mehrere Schwachstellen in Mattermost ausnutzen, um falsche Informationen anzuzeigen, Informationen offenzulegen, Sicherheitskontrollen zu umgehen und eine Denial-of-Service-Situation zu erzeugen.
GHSA-2v3w-6g35-5f9vMattermost fails to properly validate User-Agent header tokens2026-03-16ghsa · osvUS
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586
GO-2026-4725Mattermost fails to properly validate User-Agent header tokens in github.com/mattermost/mattermost-server2026-03-26vendor · osvUS
Mattermost fails to properly validate User-Agent header tokens 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 v5.3.2-0.20260129181235-1346cf529aef.

also known as (6)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu osv cert_bund NVD CVE.org MITRE

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

references (3)

External citations — patches, advisories, analysis.

scry

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