Mattermost 11.3.0/11.2.2/10.11.10: Authenticated Metadata Sanitize Bypass
CVE-2026-2457 Published on March 16, 2026
WebSocket Message Spoofing via Permalink Embed Manipulation
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID: MMSA-2025-00569
Vulnerability Analysis
CVE-2026-2457 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
Origin Validation Error
The software does not properly verify that the source of data or communication is valid.
Products Associated with CVE-2026-2457
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Affected Versions
Mattermost:- Version 11.3.0, <= 11.3.0 is affected.
- Version 11.2.0, <= 11.2.2 is affected.
- Version 10.11.0, <= 10.11.10 is affected.
- Version 11.4.0 is unaffected.
- Version 11.3.1 is unaffected.
- Version 11.2.3 is unaffected.
- Version 10.11.11 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.