CVE-2026-35542 Roundcube: Bypass of remote image blocking via crafted BODY background attribute

Medium 5.3 Published 3 Apr 2026 Updated 3 Apr 2026

Attackers can bypass remote image blocking in Roundcube Webmail via crafted email attributes, leading to information disclosure or access-control bypass.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-35542?

CVE-2026-35542 is a medium-severity vulnerability in Roundcube Webmail, published on 3 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. The remote image blocking feature can be bypassed via a crafted background attribute of a BODY element in an e-mail message. This may lead to information disclosure or access-control bypass.

Weakness: CWE-669

Which versions are affected by CVE-2026-35542?

2 open source packages ship an affected version, including roundcube/roundcubemail. It affects 1 product.

Package	Affected	Fixed in
`roundcube/roundcubemail` Packagist	From `1.7-beta`	`1.7-rc5`
`roundcube/roundcubemail` Packagist	From `1.7-beta`	`1.7-rc5`

Products include Roundcube Webmail.

How do I fix CVE-2026-35542?

Upgrade roundcube/roundcubemail to 1.7-rc5 or later.

Is CVE-2026-35542 being exploited?

There is no known exploitation of CVE-2026-35542 in the wild and no public exploit code.

All Roundcube Webmail vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-35542, GHSA-5hf6-crg4-fg59, UBUNTU-CVE-2026-35542.