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.

CVSS v3 5.6 MEDIUM

5.6^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.4

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
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

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-02 18:21

Updated : 2026-09-09 21:05

NVD link : CVE-2026-84380

Mitre link : CVE-2026-84380

CVE.ORG link : CVE-2026-84380

JSON object : View

Products Affected

No product.

CWE

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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