Debian: DLA-1008-1 Moderate: Libxml2 Heap Over-Read Warning

debian lts

June 30, 2017

CVE-2017-7375 Missing validation for external entities in xmlParsePEReference CVE-2017-9047

Topics Covered

security advisory update buffer overflow Debian libxml2 heap over-read external entity

Summary

CVE-2017-9047
CVE-2017-9048
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.

CVE-2017-9049
CVE-2017-9050
libxml2 20904-GITv2.9.4-16-g0741801 is vulnerable to a heap-based
buffer over-read in the xmlDictComputeFastKey function in dict.c.