Integer Overflow or Wraparound in libxml2 affects Nokogiri

Summary

### Summary

Nokogiri v1.13.5 upgrades the packaged version of its dependency libxml2 from v2.9.13 to [v2.9.14](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.9.14).

libxml2 v2.9.14 addresses [CVE-2022-29824](https://nvd.nist.gov/vuln/detail/CVE-2022-29824). This version also includes several security-related bug fixes for which CVEs were not created, including a potential double-free, potential memory leaks, and integer-overflow.

Please note that this advisory only applies to the CRuby implementation of Nokogiri `< 1.13.5`, 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` and `libxslt` release announcements.

### Mitigation

Upgrade to Nokogiri `>= 1.13.5`.

Users who are unable to upgrade Nokogiri may also choose a more complicated mitigation: compile and link Nokogiri against external libraries libxml2 `>= 2.9.14` which will also address these same issues.

### Impact

#### libxml2 [CVE-2022-29824](https://nvd.nist.gov/vuln/detail/CVE-2022-29824)

- **CVSS3 score**: - Unspecified upstream - Nokogiri maintainers evaluate at 8.6 (High) ([CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H)). Note that this is different from the CVSS assessed by NVD. - **Type**: Denial of service, information disclosure - **Description**: In libxml2 before 2.9.14, several buffer handling functions in buf.c (xmlBuf*) and tree.c (xmlBuffer*) don't check for integer overflows. This can result in out-of-bounds memory writes. Exploitation requires a victim to open a crafted, multi-gigabyte XML file. Other software using libxml2's buffer functions, for example libxslt through 1.1.35, is affected as well. - **Fixed**: https://gitlab.gnome.org/GNOME/libxml2/-/commit/2554a24

All versions of libml2 prior to v2.9.14 are affected.

Applications parsing or serializing multi-gigabyte documents (in excess of INT_MAX bytes) may be vulnerable to an integer overflow bug in buffer handling that could lead to exposure of confidential data, modification of unrelated data, or a segmentation fault resulting in a denial-of-service.

### References

- [libxml2 v2.9.14 release notes](https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.9.14) - [CVE-2022-29824](https://nvd.nist.gov/vuln/detail/CVE-2022-29824) - [CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer](https://cwe.mitre.org/data/definitions/119.html)