CVE-2026-97687

A flaw was found in urllib3. This vulnerability allows a remote attacker on the network to intercept and alter data transmitted through an HTTPS proxy. The issue occurs when target-server Transport Layer Security (TLS) settings inadvertently overwrite the proxy's TLS configuration, which can disable certificate verification on reused connection contexts. Consequently, an attacker can impersonate the proxy to monitor or modify forwarded traffic or capture client credentials.

Red Hat has evaluated this vulnerability as having an Important impact because a network attacker can exploit corrupted TLS validation states to impersonate an HTTPS proxy, enabling complete interception and manipulation of sensitive communications as well as client credential theft. Successful exploitation depends on specialized application architectures where outgoing requests utilize an HTTPS-capable proxy alongside customized destination TLS parameters that inadvertently override proxy verification. Default Red Hat enterprise deployments that communicate directly with endpoints, utilize traditional HTTP proxies, or rely on standard CONNECT tunneling for end-to-end encryption do not expose this flaw.

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.