CVE-2017-18900 Mattermost Server is vulnerable CSV Injection
Attackers can inject malicious formulas into CSV compliance reports, potentially leading to code execution when the file is opened in spreadsheet software.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2017-18900?
CVE-2017-18900 is a critical code injection vulnerability in Mattermost Mattermost Server, published on 19 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. It allows CSV injection via a compliance report.
Weakness: CWE-74
Which versions are affected by CVE-2017-18900?
5 open source packages ship an affected version, including github.com/mattermost/mattermost-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/mattermost/mattermost-server Go | All versions | 3.10.3+incompatible, 4.0.3+incompatible |
github.com/mattermost/mattermost-server Go | All versions | 3.10.3 |
github.com/mattermost/mattermost-server Go | All versions | 3.10.3 |
github.com/mattermost/mattermost-server Go | From 4.0.0 | 4.0.3 |
github.com/mattermost/mattermost-server Go | From 4.0.0 | 4.0.3 |
Products include Mattermost Mattermost Server.
How do I fix CVE-2017-18900?
Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 3.10.3+incompatible, 4.0.3+incompatible, 3.10.3 or 4.0.3.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2017-18900 being exploited?
There is no known exploitation of CVE-2017-18900 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-8q4v-35v6-g8wr, GO-2026-4303.