Time-of-check time-of-use vulnerability in common teams API_CVE-2026-20796

{
    "lastseen": "",
    "description": "Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549",
    "published": "2026-02-13T10:30:03.445Z",
    "modified": "2026-02-13T10:30:03.445Z",
    "type": "cve",
    "title": "Time-of-check time-of-use vulnerability in common teams API",
    "source": "Mattermost",
    "references": "https://mattermost.com/security-updates",
    "id": "CVE-2026-20796",
    "bulletinFamily": "",
    "cwe": [
        "CWE-367"
    ],
    "cvelist": null,
    "sourceData": "Mattermost Mattermost 10.11.0",
    "sourceHref": "",
    "cvss": {
        "score": 3.1,
        "severity": "LOW",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N",
        "version": "3.1"
    },
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        "confidentialityImpact": "",
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        "availabilityImpact": "",
        "cvssV3": {
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    "href": "",
    "category_name": "CVE",
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    "product": "Mattermost",
    "version": "10.11.0",
    "vendor": "Mattermost",
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}