CVE-2026-78663 — Double flow control refund on HTTP/2 server streams in net/http
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the str…
Published: 2026-10-08 · CVSS: 9.1 · CVSS 3.1
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7