CVE-2026-84380
HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated
- State
- Published
- Severity
- 5.6 Medium
- Published
- Sep 2, 2026
- Updated
- Sep 2, 2026
- Reserved
- Sep 1, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.6 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L | GitHub_M |
Weaknesses
- CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Products
| Product | Versions |
|---|---|
httpx2pydantic |
|
References
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