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Mattermost GitHub Plugin Bot Identity Validation Bypass Allows Arbitrary GitHub Reaction Injection

Low severity GitHub Reviewed Published Dec 17, 2025 to the GitHub Advisory Database • Updated Dec 17, 2025

Package

gomod github.com/mattermost/mattermost (Go)

Affected versions

< 10.11.7-0.20251106103514-3b05384dd014
>= 11.0.0-alpha.1, < 11.1.0

Patched versions

10.11.7-0.20251106103514-3b05384dd014
11.1.0
gomod github.com/mattermost/mattermost-plugin-github (Go)
< 1.0.1-0.20250829075715-0deffcfc6bee
1.0.1-0.20250829075715-0deffcfc6bee
gomod github.com/mattermost/mattermost/server/v8 (Go)
>= 10.11.0-rc1, < 10.11.7-0.20251106103514-3b05384dd014
10.11.7-0.20251106103514-3b05384dd014

Description

Mattermost versions 10.11.x <= 10.11.6 and Mattermost GitHub plugin versions <=2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts.

References

Published by the National Vulnerability Database Dec 17, 2025
Published to the GitHub Advisory Database Dec 17, 2025
Reviewed Dec 17, 2025
Last updated Dec 17, 2025

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(13th percentile)

Weaknesses

Improper Validation of Specified Type of Input

The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type. Learn more on MITRE.

CVE ID

CVE-2025-13352

GHSA ID

GHSA-jf5h-xfw4-p8gp

Source code

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