CVE-2026-5163

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Source

https://cve.org/CVERecord?id=CVE-2026-5163

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5163.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-5163

Aliases

Published

2026-05-18T08:11:13.972Z

Modified

2026-07-08T08:05:22.958056079Z

Severity

6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N CVSS Calculator

Summary

Missing authorization check in AI message rewrite endpoint allows access to private thread content

Details

Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645

Database specific

{
    "unresolved_ranges": [
        {
            "source": "AFFECTED_FIELD",
            "extracted_events": [
                {
                    "introduced": "11.5.0"
                },
                {
                    "last_affected": "11.5.1"
                }
            ]
        }
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5163.json",
    "cna_assigner": "Mattermost",
    "cwe_ids": [
        "CWE-862"
    ]
}

References

Affected packages

Git / github.com/mattermost/mattermost

Affected ranges

Type

GIT

Repo

https://github.com/mattermost/mattermost

Events

Introduced

9f2616376582893035a7e3cb38b0fab648bba4e8

Fixed

cc4ef6863ee114bc96be4e34478ec2f0db3eac4e

Database specific

{
    "source": "CPE_RANGE",
    "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "11.5.0"
        },
        {
            "fixed": "11.5.2"
        }
    ]
}

Affected versions

v11.*

v11.5.0

v11.5.1

v11.5.2-rc1

v11.5.2-rc2

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5163.json"