CVE-2024-1402 Denial of service in mattermost mobile apps and server via emoji reactions
An attacker can crash Mattermost mobile apps and servers by sending posts with excessive non-existent custom emoji reactions.
- 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-2024-1402?
CVE-2024-1402 is a medium-severity denial of service 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 if a custom emoji reaction exists when sending it to a post and to limit the amount of custom emojis allowed to be added in a post, allowing an attacker sending a huge amount of non-existent custom emojis in a post to crash the mobile app of a user seeing the post and to crash the server due to overloading when clients attempt to retrive the aforementioned post.
Weakness: CWE-400
Which versions are affected by CVE-2024-1402?
11 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 9.1.0 | 9.1.5 |
github.com/mattermost/mattermost/server/v8 Go | From 9.1.0 | 9.1.5 |
github.com/mattermost/mattermost/server/v8 Go | From 9.2.0 | 9.2.4 |
5 more packages
github.com/mattermost/mattermost/server/v8 Go | From 9.2.0 | 9.2.4 |
mattermost Bitnami | All versions | 9.6.1 |
github.com/mattermost/mattermost-server Go | From 9.1.0+incompatible | 9.1.5+incompatible, 9.2.4+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-2024-1402?
Upgrade github.com/mattermost/mattermost/server/v8 to a fixed version for your release line: 8.1.8, 9.1.5 or 9.2.4.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-1402 being exploited?
There is no known exploitation of CVE-2024-1402 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-2024-1402, GHSA-32h7-7j94-8fc2, GO-2024-2541.