HTTP/2 CONTINUATION flood in net/http

Vulnerability Description

An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames we will process before closing a connection.

References

• https://go.dev/issue/65051
• https://go.dev/cl/576155
• https://groups.google.com/g/golang-announce/c/YgW0sx8mN3M
• https://pkg.go.dev/vuln/GO-2024-2687
• https://security.netapp.com/advisory/ntap-20240419-0009/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QRYFHIQ6XRKRYBI2F5UESH67BJBQXUPT/
• http://www.openwall.com/lists/oss-security/2024/04/05/4
• http://www.openwall.com/lists/oss-security/2024/04/03/16