The remote Debian host is missing a security-related update.
Several vulnerabilities have been found in the Apache HTTPD server. - CVE-2017-3167 Emmanuel Dreyfus reported that the use of ap_get_basic_auth_pw() by third-party modules outside of the authentication phase may lead to authentication requirements being bypassed. - CVE-2017-3169 Vasileios Panopoulos of AdNovum Informatik AG discovered that mod_ssl may dereference a NULL pointer when third-party modules call ap_hook_process_connection() during an HTTP request to an HTTPS port leading to a denial of service. - CVE-2017-7659 Robert Swiecki reported that a specially crafted HTTP/2 request could cause mod_http2 to dereference a NULL pointer and crash the server process. - CVE-2017-7668 Javier Jimenez reported that the HTTP strict parsing contains a flaw leading to a buffer overread in ap_find_token(). A remote attacker can take advantage of this flaw by carefully crafting a sequence of request headers to cause a segmentation fault, or to force ap_find_token() to return an incorrect value. - CVE-2017-7679 ChenQin and Hanno Boeck reported that mod_mime can read one byte past the end of a buffer when sending a malicious Content-Type response header.
Upgrade the apache2 packages. For the oldstable distribution (jessie), these problems have been fixed in version 2.4.10-10+deb8u9. The oldstable distribution (jessie) is not affected by CVE-2017-7659. For the stable distribution (stretch), these problems have been fixed in version 2.4.25-3+deb9u1.