CVE-2026-4858

What it is

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-21 09:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-23 16:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-21 09:16 UTC

Last modified

2026-07-23 16:10 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Analyzed

Affected

• Mattermost Server < 10.11.15
• Mattermost Server < 11.4.5
• Mattermost Server < 11.5.4
• Mattermost Server 11.6.0

Attack profile CVSS 3.1 · 8.0

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High