CVE-2019-20844 Business logic in n/a
Attackers can spoof direct-message channels by altering channel types, compromising communication integrity in Mattermost Server deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2019-20844?
CVE-2019-20844 is a medium-severity vulnerability in Mattermost Mattermost Server, published on 19 Jun 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
An issue was discovered in Mattermost Server before 5.18.0, 5.17.2, 5.16.4, 5.15.4, and 5.9.7. An attacker can spoof a direct-message channel by changing the type of a channel.
Weakness: CWE-924
Which versions are affected by CVE-2019-20844?
It affects 1 product.
Products include Mattermost Mattermost Server.
How do I fix CVE-2019-20844?
No fix has been published for CVE-2019-20844 yet. Limit exposure of the affected software until one is available.
Is CVE-2019-20844 being exploited?
There is no known exploitation of CVE-2019-20844 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-fmgg-2pgh-j54h.