CVE-2023-45802: Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST

[Stefan Eissing <icing () apache org>]

Severity: moderate

Affected versions:

- Apache HTTP Server 2.4.17 through 2.4.57

Description:

When a HTTP/2 stream was reset (RST frame) by a client, there was a time window were the request's memory resources 
were not reclaimed immediately. Instead, de-allocation was deferred to connection close. A client could send new 
requests and resets, keeping the connection busy and open and causing the memory footprint to keep on growing. On 
connection close, all resources were reclaimed, but the process might run out of memory before that.

This was found by the reporter during testing of CVE-2023-44487 (HTTP/2 Rapid Reset Exploit) with their own test 
client. During "normal" HTTP/2 use, the probability to hit this bug is very low. The kept memory would not become 
noticeable before the connection closes or times out.

Users are recommended to upgrade to version 2.4.58, which fixes the issue.

Credit:

Will Dormann of Vul Labs (finder)
David Warren of Vul Labs (finder)

References:

https://httpd.apache.org/security/vulnerabilities_24.html
https://httpd.apache.org/
https://www.cve.org/CVERecord?id=CVE-2023-45802

Timeline:

2023-10-12: reported