The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2c, does not restrict

Summary

The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2c, does not restrict request-header length, which allows remote attackers to cause a denial of service (memory consumption) via crafted CONTINUATION frames in an HTTP/2 request.

Timeline

1. Dec 5, 2016, 7:00 PM UTCCVE published
2. Dec 12, 2016Public exploit on Exploit-DB

   EDB-40909

3. Aug 6, 2024, 2:34 AM UTCRecord last updated
4. Oct 28, 2026EPSS reached 10%

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

Affected versions

• Apache Software Foundation Apache HTTP Server

  2.4.17 - 2.4.23

References 28