CVE-2017-9047

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.

• How can I get the fixes?
• What do statuses mean?
• Patch details

References

• MITRE
• NVD
• Launchpad
• Debian

Related Ubuntu Security Notices (USN)

• USN-3424-1
• libxml2 vulnerabilities
• 19 September 2017
• USN-3424-2
• libxml2 vulnerabilities
• 10 October 2017

Other references

• http://www.openwall.com/lists/oss-security/2017/05/15/1
• https://www.cve.org/CVERecord?id=CVE-2017-9047