Httpx2
Monthly
Memory exhaustion via unbounded decompression in HTTPX2 (all versions before 2.12.0) allows any HTTP server the client contacts to cause severe memory pressure or out-of-memory process termination by returning a crafted compressed response body. The content decoders in `_decoders.py` call `decompress()` without a size cap, so a single 64 KiB compressed chunk can inflate to approximately 64 MiB in one allocation across gzip, deflate, brotli, and zstd encodings - all enabled by default. No active exploitation is confirmed in CISA KEV, and no public proof-of-concept is referenced, but the decompression-bomb technique is well understood and trivially reproducible.
HTTPX2's SOCKS5 proxy implementation omits TLS negotiation for WebSocket Secure (wss://) origins, exposing the full WebSocket session - opening handshake, query parameters, Authorization headers, cookies, and message frames - in plaintext to anyone who can observe or control the proxy path. Affected are applications using Client.websocket() or AsyncClient.websocket() in HTTPX2 versions 2.6.0 through 2.9.1 when routing through a SOCKS5 proxy. An adjacent-network attacker can passively eavesdrop on or actively modify traffic, and can impersonate the WebSocket server due to the missing certificate verification step. No public exploit code has been identified at time of analysis and this CVE does not appear in the CISA KEV catalog.
HTTP request smuggling in pydantic's HTTPX2 Python client library, all versions prior to 2.11.0, arises because Request._prepare() in _models.py appends a Content-Length header even when a caller-supplied Transfer-Encoding header is already present, producing HTTP/1.1 requests with two conflicting framing headers simultaneously. Downstream intermediaries such as reverse proxies or API gateways that resolve the Content-Length vs. Transfer-Encoding ambiguity differently from the upstream server can misparse request boundaries, enabling request smuggling or connection desynchronization affecting co-located sessions. No public exploit code or active exploitation has been identified at time of analysis; a vendor-released patch is available in v2.11.0.
CRLF injection in httpx2 (pydantic's next-generation Python HTTP client) before v2.11.0 allows manipulation of multipart/form-data part headers when attacker-controlled data reaches the `content_type` or custom headers fields of the `files=` parameter. `FileField.render_headers()` in `_multipart.py` interpolates these values directly into raw header bytes without stripping CR or LF characters, enabling injection of fabricated headers into multipart parts. No public exploit is identified at time of analysis; the vendor-released patch is v2.11.0.
Quadratic CPU exhaustion in HTTPX2's Server-Sent Events parser allows a malicious or compromised SSE endpoint to deny service to Python applications using httpx2.Client.sse() or httpx2.AsyncClient.sse() in versions 2.5.0 through 2.9.x. The _SSELineDecoder.decode() method in _sse.py repeatedly copies and rescans its entire in-memory buffer each time a new chunk arrives for an unterminated line, producing O(n²) processing work proportional to the length of the crafted line. A crafted stream can consume excessive CPU, blocking a synchronous worker thread indefinitely or starving an asynchronous event loop. No public exploit identified at time of analysis; a vendor-released patch is available in version 2.10.0.
Memory exhaustion via unbounded decompression in HTTPX2 (all versions before 2.12.0) allows any HTTP server the client contacts to cause severe memory pressure or out-of-memory process termination by returning a crafted compressed response body. The content decoders in `_decoders.py` call `decompress()` without a size cap, so a single 64 KiB compressed chunk can inflate to approximately 64 MiB in one allocation across gzip, deflate, brotli, and zstd encodings - all enabled by default. No active exploitation is confirmed in CISA KEV, and no public proof-of-concept is referenced, but the decompression-bomb technique is well understood and trivially reproducible.
HTTPX2's SOCKS5 proxy implementation omits TLS negotiation for WebSocket Secure (wss://) origins, exposing the full WebSocket session - opening handshake, query parameters, Authorization headers, cookies, and message frames - in plaintext to anyone who can observe or control the proxy path. Affected are applications using Client.websocket() or AsyncClient.websocket() in HTTPX2 versions 2.6.0 through 2.9.1 when routing through a SOCKS5 proxy. An adjacent-network attacker can passively eavesdrop on or actively modify traffic, and can impersonate the WebSocket server due to the missing certificate verification step. No public exploit code has been identified at time of analysis and this CVE does not appear in the CISA KEV catalog.
HTTP request smuggling in pydantic's HTTPX2 Python client library, all versions prior to 2.11.0, arises because Request._prepare() in _models.py appends a Content-Length header even when a caller-supplied Transfer-Encoding header is already present, producing HTTP/1.1 requests with two conflicting framing headers simultaneously. Downstream intermediaries such as reverse proxies or API gateways that resolve the Content-Length vs. Transfer-Encoding ambiguity differently from the upstream server can misparse request boundaries, enabling request smuggling or connection desynchronization affecting co-located sessions. No public exploit code or active exploitation has been identified at time of analysis; a vendor-released patch is available in v2.11.0.
CRLF injection in httpx2 (pydantic's next-generation Python HTTP client) before v2.11.0 allows manipulation of multipart/form-data part headers when attacker-controlled data reaches the `content_type` or custom headers fields of the `files=` parameter. `FileField.render_headers()` in `_multipart.py` interpolates these values directly into raw header bytes without stripping CR or LF characters, enabling injection of fabricated headers into multipart parts. No public exploit is identified at time of analysis; the vendor-released patch is v2.11.0.
Quadratic CPU exhaustion in HTTPX2's Server-Sent Events parser allows a malicious or compromised SSE endpoint to deny service to Python applications using httpx2.Client.sse() or httpx2.AsyncClient.sse() in versions 2.5.0 through 2.9.x. The _SSELineDecoder.decode() method in _sse.py repeatedly copies and rescans its entire in-memory buffer each time a new chunk arrives for an unterminated line, producing O(n²) processing work proportional to the length of the crafted line. A crafted stream can consume excessive CPU, blocking a synchronous worker thread indefinitely or starving an asynchronous event loop. No public exploit identified at time of analysis; a vendor-released patch is available in version 2.10.0.