Mattermost 10-11.3.x Auth, Big Password DoS
CVE-2026-24458 Published on March 16, 2026
DoS attack via login attempts with multi-megabyte passwords
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advisory ID: MMSA-2026-00587
Vulnerability Analysis
CVE-2026-24458 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
Allocation of Resources Without Limits or Throttling
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.
Products Associated with CVE-2026-24458
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Affected Versions
Mattermost:- Version 11.3.0, <= 11.3.0 is affected.
- Version 11.2.0, <= 11.2.2 is affected.
- Version 10.11.0, <= 10.11.10 is affected.
- Version 11.4.0 is unaffected.
- Version 11.3.1 is unaffected.
- Version 11.2.3 is unaffected.
- Version 10.11.11 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.