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Apache HTTP Server: DoS in HTTP/2 with initial windows size 0

Apache HTTP Server · CVE-2023-43622
0 news outlets1 CERTs and agencies0 researchers

What is it?

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout. This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

Evidence

CERTs and agencies (7)

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
Not scored
EPSS
68.8%
First seen
2 d ago
Status
confirmed

All Apache vulnerabilities