CVE-2025-13523: Cross-Site Scripting (XSS) via Unescaped Display Names in Mattermost Confluence Plugin OAuth2 Flow

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-06 · updated 2026-06-17
Weakness: CWE-79

Description

Mattermost Confluence plugin version <1.7.0 fails to properly escape user-controlled display names in HTML template rendering which allows authenticated Confluence users with malicious display names to execute arbitrary JavaScript in victim browsers via sending a specially crafted OAuth2 connection link that, when visited, renders the attacker's display name without proper sanitization. Mattermost Advisory ID: MMSA-2025-00557

Affected products

Mattermost Confluence Plugin: from 1.0.0 before 1.7.0 — fixed in 1.7.0

How to fix

Upgrade to a fixed version: Mattermost Confluence Plugin 1.7.0. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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