HTTP Client Vulnerability in Python Library Affects Multi-Part Header Handling
CVE-2026-84379

5.3MEDIUM

Key Information:

Vendor

Pydantic

Status
Httpx2
Vendor
CVE Published:
2 September 2026

What is CVE-2026-84379?

Prior to version 2.11.0, the HTTPX2 Python library contained a vulnerability in the FileField.render_headers() function. This issue allowed attacker-controlled content_type values and custom headers to be interpolated directly into multipart/form-data part headers without proper validation. An attacker could exploit this flaw by injecting CR or LF characters into header names or values, potentially manipulating part semantics or bypassing validation checks, which could lead to unexpected behavior in downstream parsers processing multipart data. Users are advised to upgrade to version 2.11.0 to mitigate these vulnerabilities.

Affected Version(s)

httpx2 < 2.11.0

References

https://github.com/pydantic/httpx2/security/advisories/GH...
x_refsource_CONFIRM
https://github.com/pydantic/httpx2/pull/1142
x_refsource_MISC
https://github.com/pydantic/httpx2/commit/de96d810ee4e309...
x_refsource_MISC

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.