Impact

Rapidly creating and cancelling streams (HEADERS frame immediately followed by RST_STREAM) without bound cause denial of service.

See https://www.cve.org/CVERecord?id=CVE-2023-44487 for details.

Patches

nghttp2 v1.57.0 mitigates this vulnerability by default.

Workarounds

If upgrading to nghttp2 v1.57.0 is not possible, implement nghttp2_on_frame_recv_callback, and check and count RST_STREAM frames. If excessive number of RST_STREAM are received, then take action, such as dropping connection silently, or call nghttp2_submit_goaway and gracefully terminate the connection.

References

The following commit mitigates this vulnerability:

• 72b4af6