CVE-2026-24458
Published: 16 March 2026
Summary
CVE-2026-24458 is a high-severity Allocation of Resources Without Limits or Throttling (CWE-770) vulnerability in Mattermost Mattermost Server. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 18.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
This control implements explicit throttling on session allocation, addressing the weakness of allocating resources without limits.
Plan testing exercises resource allocation limits and throttling during simulated failures, directly addressing weaknesses that allow unbounded resource use.
Contingency plan updates ensure recovery strategies address unbounded resource allocation, making it harder for attackers to exploit lack of throttling to cause prolonged outages.
Provides continuity when unbounded resource allocation at the primary site leads to exhaustion and downtime.
Alternate services allow operations to continue when primary allocation of resources lacks limits or throttling.
Explicit planning of security-related actions requires defining limits, windows, and resource allocations, making allocation without throttling far less likely.
Measures of performance include tracking allocation behavior and throttling effectiveness, reducing the window for resource exhaustion attacks.
Imposes an inactivity-based limit on network resource allocation, throttling the number of concurrently held connections.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct resource exhaustion DoS via unauthenticated exploitation of input handling flaw in public-facing server application (CWE-770).
NVD Description
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
Deeper analysisAI
CVE-2026-24458 is a denial-of-service vulnerability in Mattermost versions 11.3.x up to and including 11.3.0, 11.2.x up to 11.2.2, and 10.11.x up to 10.11.10. The issue arises from the server's failure to properly handle very long passwords during login attempts, allowing multi-megabyte passwords to cause excessive CPU and memory consumption. Mapped to CWE-770 (Allocation of Resources Without Limits or Throttling), it carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and was published on 2026-03-16.
Unauthenticated attackers with network access can exploit this vulnerability by sending repeated login requests containing multi-megabyte passwords. Successful exploitation leads to server resource overload, resulting in degraded performance or complete denial of service without requiring privileges, user interaction, or authentication.
Mattermost Advisory MMSA-2026-00587 provides details on the issue, with further information available at https://mattermost.com/security-updates. Security practitioners should review this advisory for recommended patches and mitigation steps.
Details
- CWE(s)