CVE-2026-6734

A flaw was found in undici. When using Socks5ProxyAgent, undici incorrectly reuses a single connection pool across different origins. This can lead to cross-origin request routing, where sensitive credentials and data intended for one destination are sent to another. Consequently, responses from unintended origins may be trusted, and secure HTTPS connections could be silently downgraded to unencrypted HTTP, resulting in information disclosure and data integrity issues.

This is rated as an Important security flaw. The undici library, when configured with Socks5ProxyAgent to handle requests for multiple origins, incorrectly reuses connection pools. This can lead to sensitive data and credentials being misrouted to unintended destinations, potentially downgrading HTTPS connections to HTTP and compromising data integrity and confidentiality. Red Hat products utilizing undici with Socks5ProxyAgent in multi-origin scenarios are affected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

The single most impactful mitigation is applying network egress controls to restrict which external destinations affected applications can reach. Because the vulnerability causes requests to be misrouted to wrong origins, limiting the set of reachable origins directly reduces the attack surface. These controls collectively limit the blast radius of the connection pool misrouting — the attacker must compromise one of the explicitly allowed destinations rather than any arbitrary origin — but they do not fix the underlying logic bug.