CVE-2026-114730
Description
A flaw was found in Roundcube Webmail. The application's internal URL validation mechanism fails to properly block certain IPv6 address representations, including transition prefixes and unspecified addresses. A remote attacker can exploit this flaw by submitting a crafted URL to bypass Server-Side Request Forgery (SSRF) protections. This allows the server to make unauthorized requests to internal loopback, link-local, or cloud metadata endpoints, potentially leading to sensitive information disclosure.
Statement
This vulnerability is rated as an Important severity flaw because an unauthenticated remote attacker can bypass destination host restrictions and query internal services or cloud instance metadata. Such cross-boundary requests can expose sensitive deployment details and internal endpoints directly from the host application. Roundcube is not included in supported Red Hat Enterprise Linux offerings or enterprise products, and is distributed solely via community projects such as Fedora and EPEL.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
Frequently Asked Questions
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