CVE-2026-6062
Received Received - Intake
Subscription Hijacking in Mattermost

Publication date: 2026-06-22

Last updated on: 2026-06-22

Assigner: Mattermost, Inc.

Description
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650
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Meta Information
Published
2026-06-22
Last Modified
2026-06-22
Generated
2026-06-22
AI Q&A
2026-06-22
EPSS Evaluated
N/A
NVD
CVE-2026-6062
EUVD
EUVD-2026-38250
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
mattermost mattermost to 11.5.5 (inc)
mattermost mattermost to 11.6.2 (inc)
mattermost mattermost to 11.7.0 (inc)
mattermost mattermost to 10.11.17 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-639 The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
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Executive Summary

This vulnerability exists in certain versions of Mattermost where the system fails to validate channel ownership before allowing edits to existing subscriptions. Specifically, an authenticated attacker can hijack subscriptions from channels they do not have access to by sending a crafted PUT request to the subscription edit endpoint.

Impact Analysis

The vulnerability allows an attacker with authentication to hijack subscriptions from channels they should not have access to. This can lead to unauthorized access to information or notifications from those channels, potentially compromising confidentiality and integrity of data within the Mattermost environment.

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