Roundcube Webmail up to 1.5.13/1.6.13 SVG Content resource transfer

Summaryinfo

A vulnerability has been found in Roundcube Webmail up to 1.5.13/1.6.13 and classified as problematic. Affected is an unknown function of the component SVG Content Handler. This manipulation causes resource transfer. This vulnerability is tracked as CVE-2026-35543. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Roundcube Webmail up to 1.5.13/1.6.13. It has been declared as problematic. Affected by this vulnerability is an unknown part of the component SVG Content Handler. The manipulation with an unknown input leads to a resource transfer vulnerability. The CWE definition for the vulnerability is CWE-669. The product does not properly transfer a resource/behavior to another sphere, or improperly imports a resource/behavior from another sphere, in a manner that provides unintended control over that resource. As an impact it is known to affect confidentiality. The summary by CVE is:

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. The remote image blocking feature can be bypassed via SVG content (with animate attributes) in an e-mail message. This may lead to information disclosure or access-control bypass.

The advisory is shared at roundcube.net. This vulnerability is known as CVE-2026-35543 since 04/03/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 304887 (Linux Distros Unpatched Vulnerability : CVE-2026-35543), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.5.14 or 1.6.14 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 1a63e01542bff42aaa71c00c4c279a09ef31f20c is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (304887) and CERT Bund (WID-SEC-2026-0789). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Open Source Roundcube

Productinfo

Type

• Mail Client Software

Vendor

• Roundcube

Name

• Webmail

Version

• 1.5.0
• 1.5.1
• 1.5.2
• 1.5.3
• 1.5.4
• 1.5.5
• 1.5.6
• 1.5.7
• 1.5.8
• 1.5.9
• 1.5.10
• 1.5.11
• 1.5.12
• 1.5.13
• 1.6.0
• 1.6.1
• 1.6.2
• 1.6.3
• 1.6.4
• 1.6.5
• 1.6.6
• 1.6.7
• 1.6.8
• 1.6.9
• 1.6.10
• 1.6.11
• 1.6.12
• 1.6.13

License

• free

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion