CVE-2026-78669: Go Standard Library Net/http

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.

Affected products

• Go Standard Library Net/http: before 1.26.9 (fixed in 1.26.9)
• Go Standard Library net/http/internal/http2: from 1.27.0-0, before 1.27.2 (fixed in 1.27.2)
• Golang.org/x/net golang.org/x/net/http2: before 0.60.0 (fixed in 0.60.0)

Published 2026-10-08. Last modified 2026-10-09.