A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801. The function xmlSnprintfElementContent in valid.c is supposed to recursively dump the element content definition into a char buffer 'buf' of size 'size'. The variable len is assigned strlen(buf). If the content->type is XML_ELEMENT_CONTENT_ELEMENT, then (i) the content->prefix is appended to buf (if it actually fits) whereupon (ii) content->name is written to the buffer. However, the check for whether the content->name actually fits also uses 'len' rather than the updated buffer length strlen(buf). This allows us to write about "size" many bytes beyond the allocated memory. This vulnerability causes programs that use libxml2, such as PHP, to crash.

Affected: Ubuntu:14.04:LTS: libxml2, Ubuntu:16.04:LTS: libxml2

It was discovered that a type confusion error existed in libxml2. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-0663)

It was discovered that libxml2 did not properly validate parsed entity references. An attacker could use this to specially construct XML data that could expose sensitive information. (CVE-2017-7375)

It was discovered that a buffer overflow existed in libxml2 when handling HTTP redirects. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-7376)

Marcel Böhme and Van-Thuan Pham discovered a buffer overflow in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code. (CVE-2017-9047)

Marcel Böhme and Van-Thuan Pham discovered a buffer overread in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service. (CVE-2017-9048)

Marcel Böhme and Van-Thuan Pham discovered multiple buffer overreads in libxml2 when handling parameter-entity references. An attacker could use these to specially construct XML data that could cause a denial of service. (CVE-2017-9049, CVE-2017-9050)