Pydantic HTTPX2/httpcore2 up to 2.9.1 SOCKS Proxy socks_proxy.py Client.websocket/AsyncClient.websocket certificate validation

Summaryinfo

A vulnerability categorized as problematic has been discovered in Pydantic HTTPX2 and httpcore2 up to 2.9.1. This vulnerability affects the function Client.websocket/AsyncClient.websocket of the file src/httpcore2/httpcore2/_sync/socks_proxy.py of the component SOCKS Proxy. The manipulation results in certificate validation. This vulnerability is known as CVE-2026-84381. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Pydantic HTTPX2 and httpcore2 up to 2.9.1. Affected is the function Client.websocket/AsyncClient.websocket of the file src/httpcore2/httpcore2/_sync/socks_proxy.py of the component SOCKS Proxy. The manipulation with an unknown input leads to a certificate validation vulnerability. CWE is classifying the issue as CWE-295. The product does not validate, or incorrectly validates, a certificate. This is going to have an impact on integrity. CVE summarizes:

HTTPX2 is a next generation HTTP client for Python. Prior to 2.10.0, httpcore2 fails to start TLS in src/httpcore2/httpcore2/_sync/socks_proxy.py and src/httpcore2/httpcore2/_async/socks_proxy.py when the remote origin uses wss through a SOCKS5 proxy because the TLS upgrade condition only recognizes https. HTTPX2 exposes the flaw through Client.websocket() and AsyncClient.websocket() from 2.6.0 through 2.9.1, so the opening handshake, query parameters, Authorization headers, cookies, and subsequent frames can cross the proxy path in plaintext without certificate verification. An attacker controlling or observing that path can read or modify traffic and impersonate the WebSocket server. This issue is fixed in httpcore2 2.10.0 and HTTPX2 2.10.0.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-84381 since 09/01/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1587.003.

Upgrading to version 2.10.0 eliminates this vulnerability.

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Productinfo

Vendor

• Pydantic

Name

• httpcore2
• HTTPX2

Version

• 2.9.0
• 2.9.1

Website

• Product: https://github.com/pydantic/httpx2/

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