Medium severity · published Jun 26, 2026
CVE-2026-13426
Client4 fails to validate path parameters
5.4
CVSS
0.3%
EPSS
No
On KEV
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
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GI
github.com/mattermost/mattermost/server/public · Mattermost
v0.0.0 before v0.1.22 · source: vendor
Affected product
GI
github.com/mattermost/mattermost/server/public
Mattermost