CVE-2025-11777Network attack vector

Cross-team metadata disclosure via unsanitized API response

Published Nov 13, 2025 · Updated Nov 13, 2025

Improper authorization in Mattermost 10.11.0 through 10.11.3 and 10.5.0 through 10.5.11 allows remote authenticated users to read cross-team data. The Add Channel Member handler returns other users' channel-member objects without sanitizing LastViewedAt and LastUpdateAt timestamps. A low-privileged account belonging to one team can query another team's user metadata and channel membership information; no integrity or availability impact is reported.

CVSS severity3.1
Low
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

Improper authorization in Mattermost 10.11.0 through 10.11.3 and 10.5.0 through 10.5.11 allows remote authenticated users to read cross-team data. The Add Channel Member handler returns other users' channel-member objects without sanitizing LastViewedAt and LastUpdateAt timestamps. A low-privileged account belonging to one team can query another team's user metadata and channel membership information; no integrity or availability impact is reported.

The record

CVE
CVE-2025-11777
Published
Nov 13, 2025
Updated
Nov 13, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863, T1087
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 13, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 13, 2025Record 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 <=10.11.3
  2. Affected versionversion=10.5.0 <=10.5.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.3; version=10.5.0 <=10.5.11

Published CVSS scores

3.1MattermostCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
4.3NIST NVDCVSS: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-863Incorrect Authorization
T1087Account Discovery

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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