CVE-2026-84380

HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.

• CWE-444

• https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab
• https://github.com/pydantic/httpx2/pull/1137
• https://github.com/pydantic/httpx2/releases/tag/v2.11.0
• https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566

Published

Sep 2, 2026

Last Modified

Sep 2, 2026

Status

Received

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2026-84375js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 u…7.5
• CVE-2026-84376Astro is a web framework for content-driven websites. Prior …6.3
• CVE-2026-84377LiteLLM is a proxy server (AI Gateway) to call LLM APIs in O…6.5
• CVE-2026-84378HTTPX2 is a next generation HTTP client for Python. From 2.5…5.9
• CVE-2026-84379HTTPX2 is a next generation HTTP client for Python. Prior to…5.3
• CVE-2026-8438The All-In-One Security (AIOS) – Security and Firewall plugi…7.2
• CVE-2026-84381HTTPX2 is a next generation HTTP client for Python. Prior to…8.1
• CVE-2026-84382HTTPX2 is a next generation HTTP client for Python. Prior to…7.5
• CVE-2026-84394fast-uri accepts a host that contains an unbalanced or mispl…7.5
• CVE-2026-8441The WP Review Slider Pro plugin for WordPress is vulnerable …7.5
• CVE-2026-8442The WP Review Slider Pro plugin for WordPress is vulnerable …8.1
• CVE-2026-84423A vulnerability has been found in Casdoor up to 4.0.0. This …7.3