Bug 2245153 (CVE-2023-43622) - CVE-2023-43622 httpd: mod_http2: DoS in HTTP/2 with initial window size 0
Summary: CVE-2023-43622 httpd: mod_http2: DoS in HTTP/2 with initial window size 0
Keywords:
Status: NEW
Alias: CVE-2023-43622
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2245323 2245890
Blocks: 2245154
TreeView+ depends on / blocked
 
Reported: 2023-10-19 19:27 UTC by Anten Skrabec
Modified: 2025-05-16 08:28 UTC (History)
12 users (show)

Fixed In Version: mod_http2 2.0.23
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2024:2368 0 None None None 2024-04-30 10:05:54 UTC

Description Anten Skrabec 2023-10-19 19:27:30 UTC 
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.

References:
https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2023-43622
https://www.openwall.com/lists/oss-security/2023/10/19/5
Comment 2 msiddiqu 2023-10-20 10:41:52 UTC 
References: 
 
https://httpd.apache.org/security/vulnerabilities_24.html
Comment 3 Guilherme de Almeida Suckevicz 2023-10-20 19:33:28 UTC 
Created httpd tracking bugs for this issue:

Affects: fedora-all [bug 2245323]
Comment 4 Guilherme de Almeida Suckevicz 2023-10-24 13:50:56 UTC 
Created mod_http2 tracking bugs for this issue:

Affects: fedora-all [bug 2245890]
Comment 8 errata-xmlrpc 2024-04-30 10:05:52 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2024:2368 https://access.redhat.com/errata/RHSA-2024:2368
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