The vulnerability CVE-2025-66471 affects the python-urllib3 package's Streaming API, which improperly handles highly compressed data. This flaw was identified and addressed by Red Hat in their security advisory RHSA-2026:11722. The issue is rated as having an important security impact by Red Hat Product Security. The advisory specifically targets Red Hat Enterprise Linux Server Extended Life Cycle Support Extension 6 on multiple architectures. The vulnerability is related to CWE-409 (Improper Locking), indicating potential concurrency or resource handling issues in the streaming API when processing compressed data.

Improper handling of highly compressed data by the urllib3 Streaming API could lead to unexpected behavior or resource exhaustion, potentially impacting the stability or security of applications relying on this library. The exact impact details and exploitation scenarios are not provided in the advisory. Red Hat classifies the security impact as important, indicating a significant but not critical risk.

Red Hat has released updated python-urllib3 packages for Red Hat Enterprise Linux Server Extended Life Cycle Support Extension 6 that address this vulnerability. Users should apply the security update as described in Red Hat advisory RHSA-2026:11722 and the referenced article https://access.redhat.com/articles/11258. Since this is an official Red Hat security update, applying the provided patches is the recommended remediation. No additional mitigation steps are indicated in the advisory.