CVE-2026-3636Network attack vector

Authenticated team-role disclosure via unsanitized API responses

Published May 22, 2026 · Updated May 22, 2026

Information disclosure in affected Mattermost releases allows remote authenticated users to read team-member role data through team APIs. Various team API endpoints return unsanitized team-member objects instead of removing role fields for callers without elevated permissions. A valid low-privilege account is required; the exposure is limited to team-member role information, with no reported integrity or availability impact.

CVSS severity4.3
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in affected Mattermost releases allows remote authenticated users to read team-member role data through team APIs. Various team API endpoints return unsanitized team-member objects instead of removing role fields for callers without elevated permissions. A valid low-privilege account is required; the exposure is limited to team-member role information, with no reported integrity or availability impact.

The record

CVE
CVE-2026-3636
Published
May 22, 2026
Updated
May 22, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-200, T1087
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 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 <=10.11.14
  2. Affected versionversion=11.4.0 <=11.4.4
  3. Affected versionversion=11.5.0 <=11.5.3
  4. Affected versionversion=11.6.0 <=11.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.14; version=11.4.0 <=11.4.4; version=11.5.0 <=11.5.3; version=11.6.0 <=11.6.0

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1087Account Discovery

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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