High severity · published Sep 2, 2026
CVE-2026-84382
HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)
7.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 50% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HT
httpx2 · pydantic
< 2.12.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-84382
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-84382
github.com
https://github.com/pydantic/httpx2/commit/4fd0c70a3f207c618b145934792f791bccfb39f8
github.com
https://github.com/pydantic/httpx2/pull/1126
github.com
https://github.com/pydantic/httpx2/releases/tag/v2.12.0
github.com
https://github.com/pydantic/httpx2/security/advisories/GHSA-8xx6-hgc6-gc2m
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