Vulnerability · Published Apr 3, 2026 · Assigned by mitre
CVE-2026-35540
Medium 5.4
In plain English
A medium-severity security flaw 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 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.4%top 65.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to SSRF or Information Disclosure, e.g., if stylesheet links point to local network hosts.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | roundcube | 1.6.5+dfsg-1+deb12u8 | DEBIAN-CVE-2026-35540 |
| Debian:13 | roundcube | 1.6.15+dfsg-0+deb13u1 | DEBIAN-CVE-2026-35540 |
| Debian:14 | roundcube | 1.6.14+dfsg-1 | DEBIAN-CVE-2026-35540 |
| Packagist | roundcube/roundcubemail | 1.7-rc5 | GHSA-vxg2-hhgr-37fx |
| Ubuntu:25.10 | roundcube | no fix listed | UBUNTU-CVE-2026-35540 |
| Ubuntu:26.10 | roundcube | no fix listed | UBUNTU-CVE-2026-35540 |
Affected products (as reported)
Weakness: CWE-669 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/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/579b68eff90650a5c782e153debd66c765648942
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
- https://github.com/roundcube/roundcubemail/commit/27ec6cc9cb25e1ef8b4d4ef39ce76d619caa6870