Detections
Analytics
CVE-2021-31618
high
Description
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 and 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 a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.
References
https://www.oracle.com/security-alerts/cpuoct2021.html
https://www.debian.org/security/2021/dsa-4937
https://security.netapp.com/advisory/ntap-20210727-0008/
https://security.gentoo.org/glsa/202107-38
https://seclists.org/oss-sec/2021/q2/206
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html