What’s Vulnerable › Vulnerabilities

CVE-2026-74998

• Severity: high (CVSS 7.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-17 · updated 2026-09-08
• Weakness: CWE-79

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: from 1.6.0 before 1.6.18; from 1.7.0 before 1.7.3 — fixed in 1.6.18, 1.7.3

How to fix

Upgrade to a fixed version: Roundcube Webmail 1.6.18, 1.7.3. Check the vendor advisory for mitigations.

References

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

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