Dashboard / CVE-2026-18551

CVE-2026-18551

MEDIUM
MEDIUM Priority: 0.01 BB Relevance: 58/100
Published: 2026-10-16 Modified: 2026-10-29 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: High
UI: None
S: Unchanged
C: High
I: High
A: None

Description

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 validate the combination of guest and admin scheme roles which allows an authenticated attacker to escalate a guest account to team or channel admin via a crafted PUT request to the member roles API endpoint.. Mattermost Advisory ID: MMSA-2026-00752

Weakness Classification (1)

Affected Software (2)

VendorProductVersion
mattermost mattermost_server 11.7.0 – 11.7.10
mattermost mattermost_server 11.10.0

References & Advisories (1)

Bug Bounty Relevance

58 / 100
✓ Network accessible
✓ Low complexity
✓ No user interaction

CVSS Score

6.5 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploitation Probability

0.22%
Raw Score 0.002220
Percentile 12.8%
Date 2026-10-29

Intelligence Sources

nvd ref →

External Links