CVE-2026-84382: high-severity vulnerability in pydantic httpx2
HTTPX2: Streaming response decompression does not bound peak memory (decompression amplification)
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
pydantic · httpx2Related CVEs — pydantic httpx2
In the same product, most dangerous first.
CVE-2026-84379MEDIUMHTTPX2: Multipart part header injection via unvalidated file Content-Type and custom headersEPSS 0.3%CVE-2026-84378MEDIUMHTTPX2: Quadratic SSE line buffering can cause CPU denial of serviceEPSS 0.3%CVE-2026-84380MEDIUMHTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generatedEPSS 0.2%CVE-2026-84381HIGHHTTPX2: Secure WebSocket traffic sent without TLS through SOCKS proxiesEPSS 0.1%