CVE-2026-13426 Client4 fails to validate path parameters
An attacker can redirect API calls to unintended endpoints by crafting IDs with path traversal components in the Mattermost Go module.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-13426?
CVE-2026-13426 is a medium-severity path traversal vulnerability in github.com/mattermost/mattermost/server/public, published on 26 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Mattermost Go module github.com/mattermost/mattermost/server/public versions < v0.1.22 fail to validate path parameters when constructing API route paths which allows an attacker to redirect API calls to unintended endpoints via crafted IDs containing path traversal components. Mattermost Advisory ID: MMSA-2025-00532
Weakness: CWE-22
Which versions are affected by CVE-2026-13426?
How do I fix CVE-2026-13426?
No fix has been published for CVE-2026-13426 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-13426 being exploited?
There is no known exploitation of CVE-2026-13426 in the wild and no public exploit code.
Sources
Also known as GHSA-72v2-v53v-4qmm.