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Mattermost allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL

Moderate severity GitHub Reviewed Published Nov 14, 2025 to the GitHub Advisory Database • Updated Nov 17, 2025

Package

gomod github.com/mattermost/mattermost-server (Go)

Affected versions

>= 10.11.0, < 10.11.4
>= 10.5.0, < 10.5.12
>= 10.12.0, < 10.12.1

Patched versions

10.11.4
10.5.12
10.12.1
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-20250929212932-a41db04d2746
8.0.0-20250929212932-a41db04d2746

Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL.

References

Published by the National Vulnerability Database Nov 14, 2025
Published to the GitHub Advisory Database Nov 14, 2025
Reviewed Nov 17, 2025
Last updated Nov 17, 2025

Severity

Moderate

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
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

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:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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.
(5th percentile)

Weaknesses

Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Learn more on MITRE.

CVE ID

CVE-2025-55073

GHSA ID

GHSA-ff85-qw3h-g9vp

Source code

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