CVE-2026-6957

mediumpriority · track · 20EPSS 0.003 · 22 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.30% (22nd) EPSS

CVSS 4.9 · medium

Is it mine?

3 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-27

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

cvss

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

8.0

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.5–8

v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 1.2 · impact 3.6

v3.18highCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:Hsecondary · ENISA EU

v3.18highCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:Hsecondary · responsibledisclosure@mattermost.comexploitability 1.3 · impact 6

v3.14.5mediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/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-22US

affected products (3)

Products and version ranges known to be affected.

Mattermost Mattermostall versionscert_bundDEcpe:/a:mattermost:mattermost_server:-
Mattermost Mattermost≤ 0 ≤1.1.5enisa_euvdEU
mattermost legal hold≤ 1.1.5nvdUScpe:2.3:a:mattermost:legal_hold:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-1291Mattermost (plugins): Schwachstelle ermöglicht nicht spezifizierten AngriffDeutsch2026-04-27csaf · cert_bundDE
Ein Angreifer kann eine Schwachstelle in Mattermost Plugins ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd NVD CVE.org MITRE

published 2026-05-27modified 2026-06-17

references (3)

External citations — patches, advisories, analysis.

scry

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