Cyber Resilience

CVE-2025-14822

DoS in Mattermost Server 10.11.0 – 10.11.9

Published
16 January 2026
Modified
20 January 2026
Patch / advisory
CVSS Score v3.1 3.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
EPSS Score 0.0032 24th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2025-14822 is a low-severity Inefficient Algorithmic Complexity (CWE-407) vulnerability in Mattermost Mattermost Server. Its CVSS base score is 3.1 (Low).

Operationally, ranked at the 24th 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 10.11.x <= 10.11.8 fail to validate input size before processing hashtags which allows an authenticated attacker to exhaust CPU resources via a single HTTP request containing a post with thousands space-separated tokens

CWE(s)

Related Threats

CVEs Like This One

CVE-2026-21388Same 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-2026-24458Same product: Mattermost Mattermost Server
CVE-2026-2325Same product: Mattermost Mattermost Server
CVE-2024-22091Same product: Mattermost Mattermost Server
CVE-2024-28949Same product: Mattermost Mattermost Server
CVE-2024-28053Same product: Mattermost Mattermost Server
CVE-2024-2446Same product: Mattermost Mattermost Server

Affected Assets

mattermost
mattermost server
10.11.0 — 10.11.9

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SC-5 Denial-of-service Protection
  • SC-6 Resource Availability
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.2.9
  • V15.4.4

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly requires validation of input size and format before processing, which would reject the oversized hashtag token list that triggers CPU exhaustion.

prevent

Mandates safeguards that limit the effects of DoS attacks caused by resource exhaustion from a single malicious request.

prevent

Requires protection of system resources against exhaustion, mitigating the CPU impact from unvalidated large inputs.

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.

PR.PS-06 mostly match
prevents

Secure SDLC practices (code review, complexity analysis, safe algorithm selection) prevent introduction of exploitable worst-case behavior.

DE.CM-09 partial match
prevents

Runtime monitoring of software and resources can detect the performance impact of triggered worst-case complexity.

ID.RA-01 partial match
prevents

Identifying and recording algorithmic-complexity vulnerabilities directly addresses the root cause before exploitation.

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.

detects

Security testing can uncover performance issues stemming from algorithmic complexity.

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

Redundancy of processing facilities can absorb resource exhaustion from inefficient algorithms.

prevents

Secure development life cycle includes design reviews that can catch inefficient algorithms before deployment.

References