ArchLinux: 202106-23: apache: denial of service
Summary
A security issue has been found in the Apache HTTP Server (httpd)
before version 2.4.48. The Apache HTTP Server protocol handler for the
HTTP/2 protocol checks received request headers against the size
limitations as configured for the server and used for the HTTP/1
protocol as well. On violation of these restrictions, an HTTP response
is sent to the client with a status code indicating why the request was
rejected.
This rejection response was not fully initialised in the HTTP/2
protocol handler if the offending header was the very first one
received or appeared in a footer. This led to a NULL pointer
dereference on initialised memory, reliably crashing the child process.
Since such a triggering HTTP/2 request is easy to craft and submit,
this can be exploited for denial of service (DoS) of the server.
Resolution
Upgrade to 2.4.48-1.
# pacman -Syu "apache>=2.4.48-1"
The problem has been fixed upstream in version 2.4.48.
References
https://httpd.apache.org/security/vulnerabilities_24.html#CVE-2021-31618 https://svn.apache.org/viewvc?view=revision&revision=1889759 https://security.archlinux.org/CVE-2021-31618
Workaround
None.