Debian Security Advisory DSA 558-1 – Julian Reschke reported a problem in mod_dav of Apache 2 in connection with a NULL pointer dereference. When running in a threaded model, especially with Apache 2, a segmentation fault can take out a whole process and hence create a denial of service for the whole server.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/34599/dsa-558.txt
Source: https://packetstormsecurity.com/files/34599/dsa-558.txt.html

