CVE-2023-43622 Apache HTTP Server: DoS in HTTP/2 with initial windows size 0

2023-10-2306:50:51

CWE-400

apache

www.cve.org

cve-2023-43622

apache http server

dos

http/2

connection

window size

exhaust

worker resources

slow loris

fix

version 2.4.58.

7.7 High

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

27.5%

JSON

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.

CNA Affected

[
  {
    "defaultStatus": "unaffected",
    "product": "Apache HTTP Server",
    "vendor": "Apache Software Foundation",
    "versions": [
      {
        "lessThanOrEqual": "2.4.57",
        "status": "affected",
        "version": "2.4.55",
        "versionType": "semver"
      }
    ]
  }
]