Arch Linux Security Advisory ASA-202106-23 ========================================== Severity: High Date : 2021-06-09 CVE-ID : CVE-2021-31618 Package : apache Type : denial of service Remote : Yes Link : https://security.archlinux.org/AVG-2041 Summary ======= The package apache before version 2.4.48-1 is vulnerable to denial of service. 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. Workaround ========== None. Description =========== 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. Impact ====== A remote attacker could crash the HTTP server using a crafted HTTP/2 request. 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