Unchecked return value from xmlTextReaderExpand

Summary

Nokogiri 1.13.8, 1.13.9 fails to check the return value from xmlTextReaderExpand in the method Nokogiri::XML::Reader#attribute_hash. This can lead to a null pointer exception when invalid markup is being parsed.

For applications using XML::Reader to parse untrusted inputs, this may potentially be a vector for a denial of service attack.

Mitigation

Upgrade to Nokogiri >= 1.13.10.

Users may be able to search their code for calls to either XML::Reader#attributes or XML::Reader#attribute_hash to determine if they are affected.

Severity

The Nokogiri maintainers have evaluated this as High Severity 7.5 (CVSS3.1).

References

• CWE - CWE-252: Unchecked Return Value (4.9)
• CWE - CWE-476: NULL Pointer Dereference (4.9)

Credit

This vulnerability was responsibly reported by @davidwilemski.