Server-Side Request Forgery (SSRF) in Roundcube Webmail - #VU162698
Published: November 9, 2026
Vulnerability identifier: #VU162698
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause server-side requests to destinations intended to be blocked.
The vulnerability exists due to incomplete address validation in Roundcube Webmail's is_local_url() SSRF filter when evaluating 6to4 addresses in the 2002::/16 range. A remote attacker can supply a URL containing a crafted 6to4 address to bypass the filter and induce a server-side request to a restricted destination.
Affected software
Roundcube Webmail
Remediation
Install security update from vendor's website.
Roundcube Webmail - addressed in versions 1.6.21, 1.7.6