GHSA-xc9x-jj77-9p9j

## Summary

Nokogiri upgrades its dependency libxml2 as follows: - Nokogiri v1.15.6 upgrades libxml2 to [2.11.7](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.11.7) from 2.11.6 - Nokogiri v1.16.2 upgrades libxml2 to [2.12.5](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.12.5) from 2.12.4

libxml2 v2.11.7 and v2.12.5 address the following vulnerability:

- CVE-2024-25062 / https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-25062 - described at https://gitlab.gnome.org/GNOME/libxml2/-/issues/604 - patched by https://gitlab.gnome.org/GNOME/libxml2/-/commit/92721970

Please note that this advisory only applies to the CRuby implementation of Nokogiri, and only if the _packaged_ libraries are being used. If you've overridden defaults at installation time to use _system_ libraries instead of packaged libraries, you should instead pay attention to your distro's `libxml2` release announcements.

JRuby users are not affected.

## Mitigation

Upgrade to Nokogiri `~> 1.15.6` or `>= 1.16.2`.

Users who are unable to upgrade Nokogiri may also choose a more complicated mitigation: compile and link Nokogiri against patched external libxml2 libraries which will also address these same issues.

## Impact

From the CVE description, this issue applies to the `xmlTextReader` module (which underlies `Nokogiri::XML::Reader`):

> When using the XML Reader interface with DTD validation and XInclude expansion enabled, processing crafted XML documents can lead to an xmlValidatePopElement use-after-free.

## Timeline

- 2024-02-04 10:35 EST - this GHSA is drafted without complete details about when the upstream issue was introduced; a request is made of libxml2 maintainers for more detailed information - 2024-02-04 10:48 EST - updated GHSA to reflect libxml2 maintainers' confirmation of affected versions - 2024-02-04 11:54 EST - v1.16.2 published, this GHSA made public - 2024-02-05 10:18 EST - updated with MITRE link to the CVE information, and updated "Impact" section - 2024-03-16 09:03 EDT - v1.15.6 published (see discussion at https://github.com/sparklemotion/nokogiri/discussions/3146), updated mitigation information - 2024-03-18 22:12 EDT - update "affected products" range with v1.15.6 information