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.

Related CVEs

CVE-2023-43622

Key Information

GHSA ID

GHSA-w2qc-22jv-44g8

Published

October 23, 2023 9:30 AM

Last Modified

February 13, 2025 6:31 PM

CVSS Score

7.5 /10

Primary Ecosystem

Unknown

Primary Package

Unknown

GitHub Reviewed

✗ No

Dataset

Last updated: July 27, 2025 6:35 AM

Data from GitHub Advisory Database. This information is provided for research and educational purposes.