CVE-2025-11777: Cross-team channel membership access

Published Nov 13, 2025
·
Updated

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint

Other sources

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API, which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint.

— GitHub

Affected Software

10 affected componentsFixes available
Mattermost Mattermost<=10.11.3, <=10.5.11
go/github.com/mattermost/mattermost-server/v6<5.3.2-0.20250905150616-ba86dfc5876b
5.3.2-0.20250905150616-ba86dfc5876b
go/github.com/mattermost/mattermost-server/v5<5.3.2-0.20250905150616-ba86dfc5876b
5.3.2-0.20250905150616-ba86dfc5876b
go/github.com/mattermost/mattermost-server<5.3.2-0.20250905150616-ba86dfc5876b
5.3.2-0.20250905150616-ba86dfc5876b
go/github.com/mattermost/mattermost<5.3.2-0.20250905150616-ba86dfc5876b
5.3.2-0.20250905150616-ba86dfc5876b
go/github.com/mattermost/mattermost/server/v8<8.0.0-20250905150616-ba86dfc5876b
8.0.0-20250905150616-ba86dfc5876b
go/github.com/mattermost/mattermost-server>=10.5.0<10.5.12
10.5.12
go/github.com/mattermost/mattermost-server>=10.11.0<10.11.4
10.11.4
Mattermost Mattermost Server>=10.5.0<10.5.12
Mattermost Mattermost Server>=10.11.0<10.11.4

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade go/github.com/mattermost/mattermost-server/v6 to a version that resolves this vulnerability.

    Fixed in 5.3.2-0.20250905150616-ba86dfc5876b
  2. Upgrade

    Upgrade go/github.com/mattermost/mattermost-server/v5 to a version that resolves this vulnerability.

    Fixed in 5.3.2-0.20250905150616-ba86dfc5876b
  3. Upgrade

    Upgrade go/github.com/mattermost/mattermost-server to a version that resolves this vulnerability.

    Fixed in 5.3.2-0.20250905150616-ba86dfc5876b
  4. Upgrade

    Upgrade go/github.com/mattermost/mattermost to a version that resolves this vulnerability.

    Fixed in 5.3.2-0.20250905150616-ba86dfc5876b
  5. Upgrade

    Upgrade go/github.com/mattermost/mattermost/server/v8 to a version that resolves this vulnerability.

    Fixed in 8.0.0-20250905150616-ba86dfc5876b
  6. Upgrade

    Upgrade go/github.com/mattermost/mattermost-server to a version that resolves this vulnerability.

    Fixed in 10.5.12
  7. Upgrade

    Upgrade go/github.com/mattermost/mattermost-server to a version that resolves this vulnerability.

    Fixed in 10.11.4
  8. Upgrade

    Upgrade Mattermost to a version that resolves this vulnerability.

    Fixed in 11.0.0
  9. Upgrade

    Upgrade Mattermost to a version that resolves this vulnerability.

    Fixed in 10.11.4
  10. Upgrade

    Upgrade Mattermost to a version that resolves this vulnerability.

    Fixed in 10.5.12

Event History

Nov 13, 2025
CVE Published
via MITRE·05:32 PM
Data Sourced
via MITRE·05:32 PM
RemedyDescriptionSeverityWeakness
Data Sourced
via NVD·06:15 PM
DescriptionSeverityWeaknessAffected Software
Advisory Published
via GitHub·06:31 PM
Data Sourced
via GitHub·06:31 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2025-11777?

The severity of CVE-2025-11777 is classified as high due to the potential unauthorized access to user metadata across teams.

2

How do I fix CVE-2025-11777?

To fix CVE-2025-11777, upgrade Mattermost to version 10.11.4 or later, or 10.5.12 or later, which contain the necessary patches.

3

What versions are affected by CVE-2025-11777?

CVE-2025-11777 affects Mattermost versions 10.11.x up to and including 10.11.3 and 10.5.x up to and including 10.5.11.

4

What type of vulnerability is CVE-2025-11777?

CVE-2025-11777 is an access control vulnerability that allows unauthorized users to access channel membership information.

5

Can CVE-2025-11777 lead to data leakage?

Yes, CVE-2025-11777 can lead to data leakage as it allows users from one team to access sensitive metadata from other teams.

Company

Resources

Contact

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