CVE-2026-78663
Double flow control refund on HTTP/2 server streams in net/http
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| Vendor | go standard library |
| Product | net/http |
| Published | Oct 8, 2026 |
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Affected Versions
Go standard library / net/http
0 < 1.26.9
Go standard library / net/http/internal/http2
1.27.0-0 < 1.27.2
golang.org/x/net / golang.org/x/net/http2
0 < 0.60.0
References
go.dev: https://go.dev/cl/847187 go.dev: https://go.dev/cl/847310 go.dev: https://go.dev/issue/81743 groups.google.com: https://groups.google.com/g/golang-announce/c/U2fTuyDJznI groups.google.com: https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs pkg.go.dev: https://pkg.go.dev/vuln/GO-2026-6612
Credits
Ali Sherif (https://www.linkedin.com/in/ali-sherif-13812b276/)