CVE-2024-24776 Incorrect Authorization leads to Channel Member Count Leak
Attackers can leak channel member counts without permissions due to missing authorization checks in the Mattermost API.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-24776?
CVE-2024-24776 is a low-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 9 Feb 2024. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Mattermost fails to check the required permissions in the POST /api/v4/channels/stats/member_count API resulting in channel member counts being leaked to a user without permissions.
Weakness: CWE-284
Which versions are affected by CVE-2024-24776?
9 open source packages ship an affected version, including github.com/mattermost/mattermost/server/v8, mattermost and github.com/mattermost/mattermost-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/mattermost/mattermost/server/v8 Go | All versions | None |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.1.8 |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.1.8 |
github.com/mattermost/mattermost/server/v8 Go | From 9.0.0 | 9.3.0 |
github.com/mattermost/mattermost/server/v8 Go | From 9.0.0 | 9.3.0 |
mattermost Bitnami | All versions | 9.6.1 |
3 more packages
github.com/mattermost/mattermost-server Go | From 9.0.0+incompatible | 9.3.0+incompatible |
github.com/mattermost/mattermost-server/v5 Go | All versions | None |
github.com/mattermost/mattermost-server/v6 Go | All versions | None |
Products include Mattermost Mattermost Server.
How do I fix CVE-2024-24776?
Upgrade github.com/mattermost/mattermost/server/v8 to a fixed version for your release line: 8.1.8 or 9.3.0.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2024-24776 being exploited?
There is no known exploitation of CVE-2024-24776 in the wild and no public exploit code.
Other vulnerabilities in Mattermost Mattermost Server
- CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers
- CVE-2025-12421 Account Takeover via Code Exchange Endpoint
- CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User
- CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards
- CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive
Sources
Also known as BIT-mattermost-2024-24776, GHSA-r833-w756-h5p2, GO-2024-2566.