Cyber Posture

CVE-2025-20051

Critical

Published: 24 February 2025

Published
24 February 2025
Modified
18 August 2025
KEV Added
Patch
CVSS Score 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0025 48.4th percentile
Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-20051 is a critical-severity Path Traversal (CWE-22) vulnerability in Mattermost Mattermost Server. Its CVSS base score is 9.9 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 48.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Data from Local System (T1005). What defenders deploy: see the NIST 800-53 controls recommended below.
Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

prevent

Directly requires input validation mechanisms at system entry points to prevent path traversal attacks via specially crafted blocks during board patching and duplication.

prevent

Mandates timely identification, reporting, and patching of software flaws like the input validation failure in vulnerable Mattermost versions.

prevent

Enforces approved access authorizations for system resources, mitigating unauthorized arbitrary file reads even if path traversal input is processed.

MITRE ATT&CK Enterprise TechniquesAI

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
Why these techniques?

Path traversal enables direct arbitrary file reads on the server, mapping to data collection from local system sources.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate input when patching and duplicating a board, which allows a user to read any arbitrary file on the system via duplicating a…

more

specially crafted block in Boards.

Deeper analysisAI

CVE-2025-20051 affects Mattermost versions 10.4.x up to and including 10.4.1, 9.11.x up to 9.11.7, 10.3.x up to 10.3.2, and 10.2.x up to 10.2.2. The vulnerability arises from a failure to properly validate input during patching and duplicating operations in the Boards feature, classified under CWE-22 (path traversal). This allows an attacker to read arbitrary files on the system by duplicating a specially crafted block. It carries a CVSS v3.1 base score of 9.9 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H), marking it as critical.

Exploitation requires an authenticated user with low privileges (PR:L) and can be performed remotely over the network (AV:N) with low complexity (AC:L) and no user interaction (UI:N). The attack has a high scope change (S:C), enabling severe impacts including high confidentiality loss through arbitrary file reads, as well as high integrity and availability disruptions (C:H/I:H/A:H).

Mattermost advisories provide further details on patches and mitigation at https://mattermost.com/security-updates. The CVE was published on 2025-02-24T08:15:10.087.

Details

CWE(s)

Affected Products

mattermost
mattermost server
9.11.0 — 9.11.8 · 10.2.0 — 10.2.3 · 10.3.0 — 10.3.3

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References