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Mattermost CVE-2025-13821

MEDIUM
Information Exposure (CWE-200)
2026-02-16 responsibledisclosure@mattermost.com
Information Disclosure Mattermost Mattermost Server Suse
5.7
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-200
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection Data exposure prevention
MITRE ATT&CK

2 techniques across 2 tactics: Collection, Discovery

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Impact

CVSS 5.7 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: Required. Exploitation requires authentication.
Exploit ScenarioDerived

An attacker (requires authentication) could exploit this vulnerability to exfiltrate password hashes and MFA secrets via profile nickname updates or email.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. [CVSS 5.7 MEDIUM]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affected Packages

go github.com/mattermost/mattermost-server fix: 5.3.2-0.20251210191531-cd17b61de41b
go github.com/mattermost/mattermost-server/v5 no fix
go github.com/mattermost/mattermost-server/v6 no fix
go github.com/mattermost/mattermost/server/v8 fix: 8.0.0-20251210191531-cd17b61de41b

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 4 packages in go

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

Classified as CWE-200 (Information Exposure). Affects Mattermost Server. Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. Mattermost Advisory ID: MMSA-2025-00560

Severity by source

NVD PRIMARY 5.7 MEDIUM
AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
SUSE MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Feb 16, 2026 - 12:16 nvd
MEDIUM 5.7

DescriptionCVE.org

Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to sanitize sensitive data in WebSocket messages which allows authenticated users to exfiltrate password hashes and MFA secrets via profile nickname updates or email verification events. Mattermost Advisory ID: MMSA-2025-00560

Executive ViewAI

Why It Matters

CVE-2025-13821 presents moderate security risk, a information exposure vulnerability rated CVSS 5.7. Sensitive information could be exposed to unauthorized parties. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict endpoint access, redact sensitive data in logs.

Threat Intelligence Overview

EPSS Score
0.0%
Top 91% exploitable
Data Quality
4 sources
Confidence: Medium
NVD CVE.org EPSS Vendor

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)CVE.org

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
openSUSE Leap 15.6 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP5 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP6 Fixed
openSUSE Leap 15.5 Fixed

References

Advisories & patches
ADVISORY https://mattermost.com/security-updates ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:0757/

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