Vulnerability · Published Apr 3, 2026 · Assigned by mitre
CVE-2026-35539
Medium 6.1
In plain English
A medium-severity cross-site scripting in Webmail from Roundcube. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.3%top 82.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | roundcube | 1.6.5+dfsg-1+deb12u8 | DEBIAN-CVE-2026-35539 |
| Debian:13 | roundcube | 1.6.15+dfsg-0+deb13u1 | DEBIAN-CVE-2026-35539 |
| Debian:14 | roundcube | 1.6.14+dfsg-1 | DEBIAN-CVE-2026-35539 |
| Packagist | roundcube/roundcubemail | 1.7-rc5 | GHSA-x4q5-8j5g-hpjc |
| Ubuntu:25.10 | roundcube | no fix listed | UBUNTU-CVE-2026-35539 |
| Ubuntu:26.10 | roundcube | no fix listed | UBUNTU-CVE-2026-35539 |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
References
- https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14
- https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
- https://github.com/roundcube/roundcubemail/commit/1b30edf5369668c92fe91dae3d52e477c808aa4f
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
- https://github.com/roundcube/roundcubemail/commit/10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1
- https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
- https://github.com/roundcube/roundcubemail/commit/d742954ccbcdee7020f8f2e7c49ce0fca5a0efab