Server-Side Request Forgery (SSRF) in Roundcube Webmail - #VU156140
Published: October 19, 2026
Vulnerability identifier: #VU156140
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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 user to bypass server-side request forgery protections and potentially access restricted network destinations.
The vulnerability exists due to insufficient address validation in is_local_url() when evaluating destinations using the NAT64 64:ff9b::/96 prefix. A remote user can supply a URL using a NAT64 representation of an otherwise restricted IPv4 destination to bypass the filter and potentially cause server-side requests to that destination.
Affected software
Roundcube Webmail
Remediation
Install security update from vendor's website.
Roundcube Webmail - addressed in versions 1.6.20, 1.7.5