vulnerability
Red Hat: CVE-2023-43622: httpd: mod_http2: DoS in HTTP/2 with initial window size 0 (Multiple Advisories)
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 8 | (AV:N/AC:L/Au:N/C:N/I:N/A:C) | Oct 23, 2023 | May 1, 2024 | Sep 10, 2025 |
Severity
8
CVSS
(AV:N/AC:L/Au:N/C:N/I:N/A:C)
Published
Oct 23, 2023
Added
May 1, 2024
Modified
Sep 10, 2025
Description
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.
Solutions
redhat-upgrade-mod_http2redhat-upgrade-mod_http2-debuginforedhat-upgrade-mod_http2-debugsource
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