Cyber Resilience

CVE-2026-2325

DoS in Mattermost Server 10.11.0 – 10.11.14

Published
18 May 2026
Modified
17 June 2026
Patch / advisory
CVSS Score v3.1 4.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
EPSS Score 0.0024 15th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-2325 is a medium-severity Allocation of Resources Without Limits or Throttling (CWE-770) vulnerability in Mattermost Mattermost Server. Its CVSS base score is 4.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 15th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-5 (Denial-of-service Protection) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to limit the size of the request body on the start meeting API endpoint, which allows an authenticated attacker to cause resource exhaustion or denial of service via…

more

a crafted oversized HTTP POST request to {{/api/v1/meetings}}.. Mattermost Advisory ID: MMSA-2026-00608

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
Why these techniques?

Directly enables application-layer DoS via resource exhaustion on an API endpoint (CWE-770).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-21388Same product: Mattermost Mattermost Server
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CVE-2026-6340Same product: Mattermost Mattermost Server
CVE-2026-6850Same product: Mattermost Mattermost Server
CVE-2025-35965Same product: Mattermost Mattermost Server
CVE-2025-14435Same product: Mattermost Mattermost Server
CVE-2024-47401Same product: Mattermost Mattermost Server
CVE-2026-4635Same product: Mattermost Mattermost Server
CVE-2026-5308Same product: Mattermost Mattermost Server
CVE-2025-8402Same product: Mattermost Mattermost Server

Affected Assets

mattermost
mattermost server
10.11.0 — 10.11.14 · 11.4.0 — 11.4.4 · 11.5.0 — 11.5.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SC-5 Denial-of-service Protection
  • SI-10 Information Input Validation
  • SC-7 Boundary Protection
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V15.4.4

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly requires mechanisms to protect against resource exhaustion from oversized or malformed requests to the meetings API.

prevent

Enforces validation of input size and format on the start-meeting POST body before allocation occurs.

prevent

Boundary protection devices can be configured to drop or throttle HTTP requests exceeding acceptable body sizes at the API endpoint.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.IR-04 mostly match
degrades

Monitoring capacity and taking action to maintain availability directly reduces unchecked resource allocation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

detects

Baseline comparison of CPU, memory and bandwidth usage helps surface uncontrolled resource allocations before they cause service degradation.

prevents

Capacity projections and elasticity measures ensure that allocation requests are bounded and can be throttled, reducing the window in which an attacker can force unbounded resource reservations.

mitigates

Defining retention periods and deletion schedules for backup copies prevents indefinite accumulation of data on storage media without corresponding resource-management controls.

mitigates

Architectural redundancy and automatic failover limit the impact of an attacker who forces excessive allocations, because spare capacity can absorb the load until the primary instance recovers.

none

Documented incident response procedures that include activation of continuity plans and controlled recovery help ensure that resource consumption triggered by an incident is bounded and managed rather than left unbounded.

none

Mandating tested continuity procedures that preserve or replace resource-limiting controls prevents an attacker from exploiting the absence of throttling mechanisms during an outage.

References