CVE-2026-28759
- Source
- https://cve.org/CVERecord?id=CVE-2026-28759
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-28759.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-28759
- Aliases
- Downstream
- Related
- Published
- 2026-05-18T06:50:07.346Z
- Modified
- 2026-07-31T18:31:06.188703956Z
- Severity
-
- 4.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
- Summary
- Insufficient authorization in shared channel membership sync allows remote cluster to remove users from arbitrary channels
- Details
-
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576
- Database specific
{ "cwe_ids": [ "CWE-863" ], "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28759.json", "cna_assigner": "Mattermost", "unresolved_ranges": [ { "extracted_events": [ { "introduced": "11.5.0" }, { "last_affected": "11.5.1" }, { "introduced": "10.11.0" }, { "last_affected": "10.11.13" }, { "introduced": "11.4.0" }, { "last_affected": "11.4.3" } ], "source": "AFFECTED_FIELD" } ] }- References
Affected packages
Git / github.com/mattermost/mattermost
Affected ranges
- Type
- GIT
- Repo
- https://github.com/mattermost/mattermost
- Events
- Database specific
{ "extracted_events": [ { "introduced": "10.11.0" }, { "fixed": "10.11.14" }, { "introduced": "11.4.0" }, { "fixed": "11.4.4" }, { "introduced": "11.5.0" }, { "fixed": "11.5.2" } ], "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "source": "CPE_RANGE" }
Affected versions
@mattermost/client@10.*
@mattermost/client@10.11.0
@mattermost/client@11.*
@mattermost/client@11.4.0
@mattermost/types@10.*
@mattermost/types@10.11.0
@mattermost/types@11.*
@mattermost/types@11.4.0
mattermost-redux@10.*
mattermost-redux@10.11.0
mattermost-redux@11.*
mattermost-redux@11.4.0
v10.*
v10.11.0
v10.11.0-rc3
v10.11.1
v10.11.1-rc1
v10.11.10
v10.11.11
v10.11.11-rc1
v10.11.11-rc2
v10.11.12
v10.11.13
v10.11.13-rc1
v10.11.14-rc1
v10.11.2
v10.11.2-rc1
v10.11.2-rc2
v10.11.3
v10.11.4
v10.11.4-rc1
v10.11.4-rc2
v10.11.4-rc3
v10.11.5
v10.11.6
v10.11.7
v10.11.8
v10.11.9
v10.11.9-rc1
v11.*
v11.4.0
v11.4.0-rc3
v11.4.1
v11.4.1-rc1
v11.4.1-rc2
v11.4.2
v11.4.3
v11.5.0
v11.5.1
v11.5.2-rc1
v11.5.2-rc2