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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 2
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Roundcube Webmail
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
|
1.6.0
|
1.6.18
|
|
Roundcube Webmail
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
|
1.7.0
|
1.7.3
|
References 5
https://github.com/roundcube/roundcubemail/commit/62d33c8a0dc3fd0dd03984220dc97…
cve@mitre.org
https://github.com/roundcube/roundcubemail/commit/a2334990c02f7cb77b1a8d6fa97fc…
cve@mitre.org
https://github.com/roundcube/roundcubemail/releases/tag/1.6.18
cve@mitre.org
https://github.com/roundcube/roundcubemail/releases/tag/1.7.3
cve@mitre.org
https://roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3
cve@mitre.org