High severity · published Apr 15, 2026
CVE-2026-28741
CSRF Protection Bypass Allows Updating a User's Authentication Method
8.1
CVSS
0.1%
EPSS
No
On KEV
Description
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to validate CSRF tokens on an authentication endpoint which allows an attacker to update a user's authentication method via a CSRF attack by tricking a user into visiting a malicious page. Mattermost Advisory ID: MMSA-2026-00625
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 3% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
10.11.0 through 10.11.12; 11.5.0 through 11.5.0; 11.4.0 through 11.4.2; 11.3.0 through 11.3.2 · source: vendor
MS
Mattermost Server · Mattermost
10.11.0 before 10.11.13; 11.3.0 before 11.3.3; 11.4.0 before 11.4.3; 11.5.0 before 11.5.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-28741
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-28741
Vendor Advisory
https://mattermost.com/security-updates
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