CVE-2017-9047: xmlsoft libxml2

Vulnerability summary

CVE-2017-9047 is a high (CVSS 7.5) vulnerability in xmlsoft libxml2. EPSS estimates a 3.16% chance of exploitation in the next 30 days, higher than 87.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 18-05-2017
   PublishedVulnerability first disclosed.
2. 14-10-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.