PT-2026-27961 · Mattermost · Mattermost

Published 2026-03-25 · Updated 2026-04-07 · CVE-2026-26233

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.4.0 and earlier Mattermost versions 11.3.1 and earlier Mattermost versions 11.2.3 and earlier Mattermost versions 10.11.11 and earlier

Description The software does not adequately limit the rate of login requests. This allows unauthenticated remote attackers to cause a denial of service, potentially leading to server crashes and restarts, through an HTTP/2 single packet attack involving a large number of parallel login requests (100+).

Recommendations Update Mattermost to a version later than 11.4.0. Update Mattermost to a version later than 11.3.1. Update Mattermost to a version later than 11.2.3. Update Mattermost to a version later than 10.11.11.

Fix

DoS

Resource Exhaustion

Weakness Enumeration

CWE-400

Related Identifiers

CVE-2026-26233

GHSA-247X-7QW8-FP98

GO-2026-4916

SUSE-SU-2026:1205-1

Affected Products

Mattermost

References · 44

• https://nvd.nist.gov/vuln/detail/CVE-2026-26233 · Security Note
• https://osv.dev/vulnerability/SUSE-SU-2026:1205-1 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-247x-7qw8-fp98 · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-4916 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://suse.com/security/cve/CVE-2026-34386 · Note
• https://twitter.com/CVEnew/status/2036911849334333745 · Twitter Post
• https://suse.com/security/cve/CVE-2026-33904 · Note
• https://suse.com/security/cve/CVE-2026-33487 · Note
• https://suse.com/security/cve/CVE-2026-29180 · Note
• https://suse.com/security/cve/CVE-2026-32286 · Note
• https://suse.com/security/cve/CVE-2026-33906 · Note
• https://suse.com/security/cve/CVE-2026-33997 · Note
• https://suse.com/security/cve/CVE-2026-26233 · Note