CVE-2025-27933 Unauthorized Private-to-Public Channel Conversion
Attackers with public-to-private conversion rights can improperly convert private channels to public, exposing private data.
- 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-2025-27933?
CVE-2025-27933 is a medium-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 21 Mar 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, 10.3.x <= 10.3.3, 9.11.x <= 9.11.8 fail to fail to enforce channel conversion restrictions, which allows members with permission to convert public channels to private ones to also convert private ones to public
Weakness: CWE-863
Which versions are affected by CVE-2025-27933?
15 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 | 8.0.0-20250218135018-e644e3c8e393 |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250218135018-e644e3c8e393 |
github.com/mattermost/mattermost/server/v8 Go | All versions | 8.0.0-20250218135018-e644e3c8e393 |
github.com/mattermost/mattermost/server/v8 Go | From 10.3.0 | 10.3.4 |
github.com/mattermost/mattermost/server/v8 Go | From 10.3.0 | 10.3.4 |
github.com/mattermost/mattermost/server/v8 Go | From 10.4.0 | 10.4.3 |
9 more packages
github.com/mattermost/mattermost/server/v8 Go | From 10.4.0 | 10.4.3 |
github.com/mattermost/mattermost/server/v8 Go | From 9.11.0 | 9.11.9 |
github.com/mattermost/mattermost/server/v8 Go | From 9.11.0 | 9.11.9 |
mattermost Bitnami | From 9.11.0 | 10.0.0, 10.5.1 |
github.com/mattermost/mattermost-server Go | All versions | 9.11.9 |
github.com/mattermost/mattermost-server Go | All versions | 9.11.9 |
github.com/mattermost/mattermost-server Go | From 9.11.0+incompatible | 9.11.9+incompatible, 10.3.4+incompatible, 10.4.3+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-2025-27933?
Upgrade github.com/mattermost/mattermost/server/v8 to a fixed version for your release line: 8.0.0-20250218135018-e644e3c8e393, 10.3.4, 10.4.3 or 9.11.9.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-27933 being exploited?
There is no known exploitation of CVE-2025-27933 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-2025-27933, GHSA-h5v9-xw2g-7hrq, GO-2025-3556.