CVE-2025-35965 DoS in Mattermost Playbooks via Excessive Task Actions
An attacker can cause a denial of service in Mattermost by submitting excessive task actions via the GraphQL API, overloading the server.
- 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-2025-35965?
CVE-2025-35965 is a medium-severity denial of service vulnerability in Mattermost Mattermost Server, published on 24 Apr 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.10 fail to validate the uniqueness and quantity of task actions within the UpdateRunTaskActions GraphQL operation, which allows an attacker to create task items containing an excessive number of actions triggered by specific posts, overloading the server and leading to a denial-of-service (DoS) condition.
Weakness: CWE-770
Which versions are affected by CVE-2025-35965?
21 open source packages ship an affected version, including github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-plugin-playbooks 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 | 8.0.0-20250218121836-2b5275d87136 |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250218121836-2b5275d87136 |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250218121836-2b5275d87136 |
github.com/mattermost/mattermost/server/v8 Go | From 10.4.0 | None |
github.com/mattermost/mattermost/server/v8 Go | From 10.4.0 | None |
15 more packages
github.com/mattermost/mattermost/server/v8 Go | From 10.5.0 | None |
github.com/mattermost/mattermost/server/v8 Go | From 10.5.0 | None |
github.com/mattermost/mattermost/server/v8 Go | From 9.11.0 | None |
github.com/mattermost/mattermost/server/v8 Go | From 9.11.0 | None |
github.com/mattermost/mattermost-plugin-playbooks Go | All versions | None |
github.com/mattermost/mattermost-plugin-playbooks Go | All versions | 1.41.0 |
github.com/mattermost/mattermost-plugin-playbooks Go | All versions | 1.41.0 |
github.com/mattermost/mattermost-plugin-playbooks Go | All versions | 1.41.0 |
github.com/mattermost/mattermost-plugin-playbooks Go | From 2.0.0 | None |
github.com/mattermost/mattermost-plugin-playbooks Go | From 2.0.0 | None |
github.com/mattermost/mattermost-server Go | From 10.4.0+incompatible | None |
github.com/mattermost/mattermost-server Go | From 10.5.0+incompatible | None |
github.com/mattermost/mattermost-server Go | From 9.11.0+incompatible | None |
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-2025-35965?
Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20250218121836-2b5275d87136 or later.
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-2025-35965 being exploited?
There is no known exploitation of CVE-2025-35965 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 GHSA-689c-xq7x-xjwf, GO-2025-3643.