CVE-2026-4635

Name: CVE-2026-4635
Creator: NVD / NIST
Published: 2026-05-22T11:16:22.747+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.17%

Last modified Jun 17, 2026

CVE-2026-4635 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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 archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637. EPSS estimates a 0.17% chance of exploitation in the next 30 days.

Description

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 archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.17%

6.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-362

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.15
Mattermost	Mattermost Server	>= 11.4.0, < 11.4.5
Mattermost	Mattermost Server	>= 11.5.0, < 11.5.4
Mattermost	Mattermost Server	>= 11.6.0, < 11.6.1

References

https://mattermost.com/security-updatesVendor Advisory

Timeline

Published: May 22, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-4635?

How severe is CVE-2026-4635?

CVE-2026-4635 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-4635?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-4635?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST