CVE-2026-75004: Roundcube Webmail

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, improper rule name quoting could lead to managesieve_disabled_actions setting bypass via a crafted rule name in a Sieve script. This issue only affects Roundcube instances using the managesieve plugin.

Affected products

• Roundcube Webmail: from 1.6.0, before 1.6.18 (fixed in 1.6.18); from 1.7.0, before 1.7.3 (fixed in 1.7.3)

Published 2026-08-17. Last modified 2026-09-08.