What’s Vulnerable › Vulnerabilities

CVE-2026-84382: HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-02 · updated 2026-09-09
• Weakness: CWE-409

Description

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

References

• https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8
• https://github.com/pydantic/httpx2/pull/1126
• https://github.com/pydantic/httpx2/releases/tag/v2.12.0
• https://github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m

Get alerted when CVE-2026-84382 or the next vulnerability affects your stack