{"id":"CVE-2026-74998","title":"In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.","summary":"In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.","severity":"high","cvss":7.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","cwe":["CWE-79"],"vendor":"roundcube","product":"webmail","affected":["webmail >= 1.6.0, < 1.6.18","webmail >= 1.7.0, < 1.7.3"],"patched":["webmail 1.7.3"],"published":"2026-08-17","updated":"2026-09-08","sourceUpdated":"2026-09-08T19:10:00.133","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74998","references":[{"url":"https://github.com/roundcube/roundcubemail/commit/62d33c8a0dc3fd0dd03984220dc9709e8e0de43b","label":"cve@mitre.org"},{"url":"https://github.com/roundcube/roundcubemail/commit/a2334990c02f7cb77b1a8d6fa97fcd9e1b5cd1fb","label":"cve@mitre.org"},{"url":"https://github.com/roundcube/roundcubemail/releases/tag/1.6.18","label":"cve@mitre.org"},{"url":"https://github.com/roundcube/roundcubemail/releases/tag/1.7.3","label":"cve@mitre.org"},{"url":"https://roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3","label":"cve@mitre.org"}],"tags":["nvd"],"epss":0.00322,"epssPercentile":0.25321,"ingestedAt":"2026-09-08T20:10:03.157Z","slug":"CVE-2026-74998","body":"## Overview\n\nIn Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.\n\n## Affected\n\n- `webmail >= 1.6.0, < 1.6.18`\n- `webmail >= 1.7.0, < 1.7.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `webmail 1.7.3`","depth":"twilight","depthScore":40,"depthScoreParts":{"impact":39.6,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}