SecuriTricks - CVE-2026-20796

Description

Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

Product(s) Impacted

Vendor	Product	Versions
Mattermost	Mattermost	10.11.0-10.11.9

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-367

Time-of-check Time-of-use (TOCTOU) Race Condition

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	mattermost	mattermost	10.11.0-10.11.9	/	/	/	/	/	/	/

References

https://mattermost.com/security-updates

CVSS Score

3.1 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: HIGH
Privileges Required: LOW
Scope: UNCHANGED
Confidentiality Impact: LOW
Integrity Impact: NONE
Availability Impact: NONE

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

View Vector String

Timeline

Published: Feb. 13, 2026, 11:16 a.m.
Last Modified: Feb. 13, 2026, 2:23 p.m.

Status : Awaiting Analysis

CVE has been marked for Analysis. Normally once in this state the CVE will be analyzed by NVD staff within 24 hours.

More info

Source

[email protected]

CVE-2026-20796