{"id":"CVE-2023-2808","aliases":["EUVD-2023-34261","GHSA-vc9q-cghx-53cj"],"status":"published","title":"Lack of URL normalization allows rendering previews for disallowed domains","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.","severity":{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00408,"percentile":0.35445,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-20"],"published":"2023-05-29T09:07:34Z","modified":"2026-10-28T02:30:54Z","products":[{"vendor":"mattermost","product":"mattermost"}],"references":[{"url":"https://mattermost.com/security-updates/","tags":["x_transferred","Vendor Advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-2808","tags":["advisory"]},{"url":"https://mattermost.com/security-updates"},{"url":"https://github.com/advisories/GHSA-vc9q-cghx-53cj"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/2xxx/CVE-2023-2808.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2023-2808","title":"Lack of URL normalization allows rendering previews for disallowed domains","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.\n\n","status":"published","published":"2023-05-29T09:07:34.768Z","modified":"2024-12-06T23:04:02.11Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:35:24.004321Z"}],"euvd":[{"id":"EUVD-2023-34261","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.\n\n","status":"published","published":"2023-05-29T09:07:34Z","modified":"2024-12-06T23:04:02Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-03T00:04:38.652605Z"}],"ghsa":[{"id":"GHSA-vc9q-cghx-53cj","title":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be...","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.\n\n","status":"published","published":"2023-05-29T12:30:18Z","modified":"2024-04-04T04:22:38Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:56:23.412856Z"}],"nvd":[{"id":"CVE-2023-2808","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.\n\n","status":"published","published":"2023-05-29T10:15:10.083Z","modified":"2026-06-17T05:53:29.43Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:08:03.795015Z"}],"osv":[{"id":"CVE-2023-2808","title":"Lack of URL normalization allows rendering previews for disallowed domains","description":"Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.\n\n","status":"published","published":"2023-05-29T09:07:34.768Z","modified":"2026-10-28T02:30:54.704911719Z","cvss":[{"version":"3.1","score":4.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:44:31.135751Z"}]}}