Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582
References (1)
Core 1
Core References
Scores
CVSS v3
3.5
EPSS
0.0003
EPSS Percentile
9.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-918
Status
published
Products (6)
Mattermost/Mattermost
10.11.0 - 10.11.13
Mattermost/Mattermost
10.11.14
Mattermost/Mattermost
11.5.0 - 11.5.1
Mattermost/Mattermost
11.5.2
Mattermost/Mattermost
11.6.0
mattermost/mattermost_server
10.11.0 - 10.11.14
Published
May 18, 2026
Tracked Since
May 18, 2026