CVE-2024-42000: Unauthorized Access to view channels' details

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-11-09 · updated 2026-06-17
Weakness: CWE-863

Description

Mattermost versions 9.10.x <= 9.10.2, 9.11.x <= 9.11.1, 9.5.x <= 9.5.9 and 10.0.x <= 10.0.0 fail to properly authorize the requests to /api/v4/channels which allows a User or System Manager, with "Read Groups" permission but with no access for channels to retrieve details about private channels that they were not a member of by sending a request to /api/v4/channels.

Affected products

Mattermost: from 9.5.0 before 9.5.10; from 9.10.0 before 9.10.3; from 9.11.0 before 9.11.2; 10.0.0, 10.0.0-rc1, 10.0.0-rc2, 10.0.0-rc3, 10.0.0-rc4 — fixed in 9.10.3, 9.11.2, 9.5.10

How to fix

Upgrade to a fixed version: Mattermost 9.10.3, 9.11.2, 9.5.10. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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