CVE-2026-75004 Security feature bypass in Webmail
Attackers can bypass disabled Sieve actions in Roundcube Webmail by crafting malicious rule names, requiring the managesieve plugin to be enabled.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-75004?
CVE-2026-75004 is a medium-severity vulnerability in Roundcube Webmail, published on 17 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-77
Which versions are affected by CVE-2026-75004?
It affects 1 product.
Products include Roundcube Webmail.
How do I fix CVE-2026-75004?
Upgrade to a fixed version.
Is CVE-2026-75004 being exploited?
There is no known exploitation of CVE-2026-75004 in the wild and no public exploit code.
Other vulnerabilities in Roundcube Webmail
Sources
Also known as DEBIAN-CVE-2026-75004, GHSA-3247-mrpv-cpmj, UBUNTU-CVE-2026-75004.