Some HTTP/2 implementations are vulnerable to a settings flood, potentially leading to a denial of service

Summary

Some HTTP/2 implementations are vulnerable to a settings flood, potentially leading to a denial of service. The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame, an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Timeline

1. Aug 13, 2019, 8:50 PM UTCCVE published
2. Aug 4, 2024, 9:54 PM UTCRecord last updated
3. Oct 28, 2026EPSS reached 10%

   FIRST estimates at least a 10% chance of exploitation in the next 30 days

Affected versions

• n/a n/a

  Version range not reported

References 25