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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
Low
Partial disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6…
security-advisories@github.com
https://github.com/pydantic/httpx2/pull/1137
security-advisories@github.com
https://github.com/pydantic/httpx2/releases/tag/v2.11.0
security-advisories@github.com
https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566
security-advisories@github.com