Description
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.
Affected products
roundcube: webmail
References5
- roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3 Vendor Advisory
- github.com/roundcube/roundcubemail/commit/62d33c8a0dc3fd0dd0398… Patch
- github.com/roundcube/roundcubemail/commit/a2334990c02f7cb77b1a8… Patch
- github.com/roundcube/roundcubemail/releases/tag/1.6.18 Release Notes
- github.com/roundcube/roundcubemail/releases/tag/1.7.3 Release Notes
Metrics
- CVSS 3.1
-
7.2
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 25 · as of 11 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
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