HTTPX2: Multipart part header injection via unvalidated file Content-Type and custom headers (CVE-2026-84379) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-84379

HTTPX2: Multipart part header injection via unvalidated file Content-Type and custom headers

Answer in brief

CVE-2026-84379 records a Unknown severity vulnerability in HTTPX2: Multipart part header injection via unvalidated file Content-Type and custom headers. The current sources do not mark it as known exploited. The current feed maps pydantic/httpx2 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 2, 2026Updated Sep 2, 2026Source checked Sep 2, 2026First seen by HOL Sep 2, 2026Material review Sep 2, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pydantic/httpx2 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pydantic/httpx2generic	< 2.11.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for pydantic/httpx2.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Sep 2, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 2, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 2, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.