CVE-2026-35539

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-03 · updated 2026-07-24
Weakness: CWE-79

Description

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.

Affected products

Roundcube Webmail: before 1.5.14; from 1.6.0 before 1.6.14 — fixed in 1.5.14, 1.6.14

How to fix

Upgrade to a fixed version: Roundcube Webmail 1.5.14, 1.6.14. Check the vendor advisory for mitigations.

References

https://github.com/roundcube/roundcubemail/commit/10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1
https://github.com/roundcube/roundcubemail/commit/1b30edf5369668c92fe91dae3d52e477c808aa4f
https://github.com/roundcube/roundcubemail/commit/d742954ccbcdee7020f8f2e7c49ce0fca5a0efab
https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14

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