CVE-2023-1776 Stored XSS via SVG attachment on Boards
Attackers can execute arbitrary scripts in victim browsers by uploading malicious SVG files to Mattermost Boards cards.
- 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-2023-1776?
CVE-2023-1776 is a high-severity cross-site scripting vulnerability in Mattermost Mattermost Server, published on 31 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
Boards in Mattermost allows an attacker to upload a malicious SVG image file as an attachment to a card and share it using a direct link to the file.
Weakness: CWE-79
Which versions are affected by CVE-2023-1776?
13 open source packages ship an affected version, including github.com/mattermost/mattermost-server, mattermost and github.com/mattermost/mattermost-server/v5. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/mattermost/mattermost-server Go | From 7.1.0 | 7.1.6 |
github.com/mattermost/mattermost-server Go | From 7.1.0 | 7.1.6 |
github.com/mattermost/mattermost-server Go | From 7.7.0 | 7.7.2 |
github.com/mattermost/mattermost-server Go | From 7.7.0 | 7.7.2 |
github.com/mattermost/mattermost-server Go | From 7.8.0 | 7.8.1 |
github.com/mattermost/mattermost-server Go | From 7.8.0 | 7.8.1 |
7 more packages
mattermost Bitnami | All versions to 7.7.1 | 7.1.6 |
github.com/mattermost/mattermost-server/v5 Go | From 5.0.0 | 7.1.6 |
github.com/mattermost/mattermost-server/v5 Go | From 5.0.0 | 7.1.6 |
github.com/mattermost/mattermost-server/v6 Go | From 3.3.0 | 7.1.6 |
github.com/mattermost/mattermost-server/v6 Go | From 3.3.0 | 7.1.6 |
github.com/mattermost/mattermost-server/v6 Go | From 6.0.0 | 7.1.6 |
github.com/mattermost/mattermost-server/v6 Go | From 6.0.0 | 7.1.6 |
Products include Mattermost Mattermost Server.
How do I fix CVE-2023-1776?
Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 7.1.6, 7.7.2 or 7.8.1.
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-2023-1776 being exploited?
There is no known exploitation of CVE-2023-1776 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-2023-1776, GHSA-63f2-6959-2pxj.