CVE-2026-28741Network attack vector

Authentication method change via missing CSRF validation

Published Apr 15, 2026 · Updated Apr 15, 2026

Cross-site request forgery in affected Mattermost servers allows remote attackers to change a user's authentication method through a malicious page. The user-authentication update API endpoint accepts a state-changing request without validating a CSRF token, causing it to run in the victim's authenticated browser context. Exploitation requires the user to visit attacker-controlled content while authenticated, and authentication transfer must be enabled for the method change to succeed.

CVSS severity6.8
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site request forgery in affected Mattermost servers allows remote attackers to change a user's authentication method through a malicious page. The user-authentication update API endpoint accepts a state-changing request without validating a CSRF token, causing it to run in the victim's authenticated browser context. Exploitation requires the user to visit attacker-controlled content while authenticated, and authentication transfer must be enabled for the method change to succeed.

The record

CVE
CVE-2026-28741
Published
Apr 15, 2026
Updated
Apr 15, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-352, T1098
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.11.0 <=10.11.12
  2. Affected versionversion=11.3.0 <=11.3.2
  3. Affected versionversion=11.4.0 <=11.4.2
  4. Affected versionversion=11.5.0 <=11.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.12; version=11.3.0 <=11.3.2; version=11.4.0 <=11.4.2; version=11.5.0 <=11.5.0

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
6.8Mattermost, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1098Account Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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