CVE-2026-74998 PUBLISHED

Assigner: mitre
Reserved: 17.08.2026 Published: 17.08.2026 Updated: 17.08.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
CVSS Score: 7.2

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	None	Integrity Impact	Low
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	Roundcube
Product	Webmail
Versions	Default: unaffected affected from 1.6.0 to 1.6.18 (excl.) affected from 1.7.0 to 1.7.3 (excl.)

References

https://roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3
https://github.com/roundcube/roundcubemail/releases/tag/1.6.18
https://github.com/roundcube/roundcubemail/commit/62d33c8a0dc3fd0dd03984220dc9709e8e0de43b
https://github.com/roundcube/roundcubemail/releases/tag/1.7.3
https://github.com/roundcube/roundcubemail/commit/a2334990c02f7cb77b1a8d6fa97fcd9e1b5cd1fb

Problem Types

CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') CWE