Is CVE-2026-26233 actively exploited?

CVE-2026-26233 has no public evidence of in-the-wild exploitation as of 2026-03-26.

What is the CVSS score for CVE-2026-26233?

CVE-2026-26233 has a CVSS score of 4.3 (MEDIUM severity). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

How do I patch CVE-2026-26233?

Patch guidance is available from mattermost security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-26233.

CVE-2026-26233 - remediation guidance & executive summary

Q: Which products are affected by CVE-2026-26233?

4 products: mattermost mattermost server, mattermost mattermost server, mattermost mattermost server, mattermost mattermost server.

Description

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Attack Vector: network
Complexity: low
Privileges: low
User Action: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: low
Weaknesses: CWE-400

Metadata

Primary Vendor: MATTERMOST
Published: 3/25/2026
Last Modified: 3/26/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

mattermost : mattermost_servermattermost : mattermost_servermattermost : mattermost_servermattermost : mattermost_server

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-26233. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-26233

View on NIST NVD

CVE-2026-26233 vulnerability