Pydantic HTTPX2 up to 2.10.x Multipart Parser _multipart.py FileField.render_headers injection

Summaryinfo

A vulnerability has been found in Pydantic HTTPX2 up to 2.10.x and classified as problematic. This impacts the function FileField.render_headers of the file src/httpx2/httpx2/_multipart.py of the component Multipart Parser. This manipulation causes injection. This vulnerability is registered as CVE-2026-84379. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Pydantic HTTPX2 up to 2.10.x. It has been declared as problematic. Affected by this vulnerability is the function FileField.render_headers of the file src/httpx2/httpx2/_multipart.py of the component Multipart Parser. The manipulation with an unknown input leads to a injection vulnerability. The CWE definition for the vulnerability is CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. As an impact it is known to affect integrity. The summary by CVE is:

HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, FileField.render_headers() in src/httpx2/httpx2/_multipart.py directly interpolates attacker-controlled content_type values and custom headers from the files= three-element (filename, content, content_type) tuple and the files= four-element (filename, content, content_type, headers) tuple into multipart/form-data part headers without validating header names or values. CR or LF characters can terminate a part header, inject additional part headers, or end the part header block early, allowing a downstream multipart parser to treat attacker-supplied lines as genuine headers and potentially alter part semantics or bypass header-based checks. This issue is fixed in version 2.11.0.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-84379 since 09/01/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

Upgrading to version 2.11.0 eliminates this vulnerability.

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Productinfo

Vendor

• Pydantic

Name

• HTTPX2

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10

Website

• Product: https://github.com/pydantic/httpx2/

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