HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-84382
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-02 19:18:08 UTC
Updated2026-09-03 15:17:35 UTC
DescriptionHTTPX2 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-409 | CWE-409 CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Pydantic Httpx2 affected < 2.12.0 Not specified

References

ReferenceSourceLinkTags
github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m [email protected] github.com
github.com/pydantic/httpx2/pull/1126 [email protected] github.com
github.com/pydantic/httpx2/releases/tag/v2.12.0 [email protected] github.com
github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8 [email protected] github.com
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