CVE-2023-43622
Published: 23 October 2023
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.
Notes
| Author | Note |
|---|---|
Priority reason: Apache developers consider this to be a low-impact issue |
|
| mdeslaur | backporting this to jammy and earlier will likely require backporting the whole 2.0.10 version of the http/2 module as it refactors how connections and streams are handled: https://github.com/apache/httpd/commit/9767274b884a110e9244f59f50bd31ff1cae2933 |
Priority
Status
| Package | Release | Status |
|---|---|---|
|
apache2 Launchpad, Ubuntu, Debian |
bionic |
Not vulnerable
(version not vulnerable)
|
| focal |
Not vulnerable
(2.4.41-4ubuntu3.14)
|
|
| jammy |
Not vulnerable
(2.4.52-1ubuntu4.6)
|
|
| lunar |
Released
(2.4.55-1ubuntu2.1)
|
|
| mantic |
Released
(2.4.57-2ubuntu2.1)
|
|
| trusty |
Not vulnerable
(http2 support not implemented)
|
|
| upstream |
Released
(2.4.58-1)
|
|
| xenial |
Not vulnerable
(http2 not built)
|
|
|
Patches: upstream: https://github.com/apache/httpd/commit/582c533c1728459eef5f8ec1a64b81fb093b26a8 |
||
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.5 |
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |