CVE-2026-84382: Pydantic HTTPX2

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

HTTPX2 is a next generation HTTP client for Python. Prior to 2.12.0, the HTTPX2 content decoders in src/httpx2/httpx2/_decoders.py fully inflate each gzip, deflate, br, or zstd network chunk before iter_bytes() or aiter_bytes() yields bounded pieces to the application. A 64 KiB compressed chunk can expand to approximately 64 MiB in one intermediate allocation, so an attacker-controlled or compromised server can cause severe memory pressure or out-of-memory process termination even when the application streams the response. This issue is fixed in version 2.12.0.

Affected products

• Pydantic HTTPX2: before 2.12.0 (fixed in 2.12.0)

Published 2026-09-02. Last modified 2026-09-09.