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.
Published: 2026-09-02
Score: 5.6 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Wed, 02 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 02 Sep 2026 18:00:00 +0000

Type Values Removed Values Added
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.
Title HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-02T18:07:36.980Z

Reserved: 2026-09-01T16:27:58.130Z

Link: CVE-2026-84380

cve-icon Vulnrichment

Updated: 2026-09-02T18:07:32.081Z

cve-icon NVD

Status : Received

Published: 2026-09-02T18:21:29.513

Modified: 2026-09-02T19:18:08.113

Link: CVE-2026-84380

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-444

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