CVE-2023-1421 Reflected XSS in OAuth flow completion endpoints
Attackers can execute scripts in victims' browsers via crafted OAuth links, potentially leading to session hijacking or unauthorized actions.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2023-1421?
CVE-2023-1421 is a low-severity cross-site scripting vulnerability in Mattermost Mattermost Server, published on 15 Mar 2023. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
A reflected cross-site scripting vulnerability in the OAuth flow completion endpoints in Mattermost allows an attacker to send AJAX requests on behalf of the victim via sharing a crafted link with a malicious state parameter.
Weakness: CWE-79
Which versions are affected by CVE-2023-1421?
1 open source package ship an affected version, including mattermost. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mattermost Bitnami | From 5.32.0 | 7.7.0 |
Products include Mattermost Mattermost Server.
How do I fix CVE-2023-1421?
Upgrade mattermost to 7.7.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2023-1421 being exploited?
There is no known exploitation of CVE-2023-1421 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-2023-1421, GHSA-mq63-cgjw-m94m.