CVE-2026-4054
Published:May 15, 2026
Updated:May 18, 2026
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link.. Mattermost Advisory ID: MMSA-2026-00630
Affected Packages
github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.4.0 <v11.4.4Fix Suggestion:
Update to version v11.4.4github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.5.0 <v11.5.2Fix Suggestion:
Update to version v11.5.2github.com/mattermost/mattermost (GO):
Affected version(s) >=v10.11.0 <v10.11.14Fix Suggestion:
Update to version v10.11.14Related Resources (1)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Improper Check for Unusual or Exceptional Conditions
EPSS
Base Score:
0.09