CVE-2026-16453

highpriority · track · 0EPSS 0.002 · 8 %ileDE
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.19% (8th) EPSS
CVSS 7.1 · high
Is it mine?
10 products
Check your exposure
Who says so?
1 sources
cert_bund

EPSS · scored 2026-10-27

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only teams, via forging the team_id or invite_id fields in the RelayState.. Mattermost Advisory ID: MMSA-2026-00727

01

cvss

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

7.1
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.5–7.1

v3.17.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 2.8 · impact 4.2
v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

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

Trackcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-472US
04

affected products (10)

Products and version ranges known to be affected.

05

advisories (1)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-4009Mattermost: Mehrere SchwachstellenDeutsch2026-10-15csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Mattermost ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um seine Privilegien zu erhöhen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren.

06

sources

Which sources assert this record, and when.

cert_bundNVDCVE.orgMITRE
published 2026-10-16modified 2026-10-16
07

references (1) nvd

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan