GitHub Security Advisory: GHSA-7rrm-v45f-jp64
Package: nokogiri (RUBYGEMS)
Severity: MODERATE (CVSS 0.0)
Vulnerable versions: < 1.11.4
Patched in: 1.11.4

Summary: Nokogiri updates packaged dependency on libxml2 from 2.9.10 to 2.9.12

Details:
### Summary

Nokogiri v1.11.4 updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

- [CVE-2019-20388](https://security.archlinux.org/CVE-2019-20388) (Medium severity)
- [CVE-2020-24977](https://security.archlinux.org/CVE-2020-24977) (Medium severity)
- [CVE-2021-3517](https://security.archlinux.org/CVE-2021-3517) (Medium severity)
- [CVE-2021-3518](https://security.archlinux.org/CVE-2021-3518) (Medium severity)
- [CVE-2021-3537](https://security.archlinux.org/CVE-2021-3537) (Low severity)
- [CVE-2021-3541](https://security.archlinux.org/CVE-2021-3541) (Low severity)

Note that two additional CVEs were addressed upstream but are not relevant to this release. [CVE-2021-3516](https://security.archlinux.org/CVE-2021-3516) via `xmllint` is not present in Nokogiri, and [CVE-2020-7595](https://security.archlinux.org/CVE-2020-7595) has been patched in Nokogiri since v1.10.8 (see #1992).

Please note that this advisory only applies to the CRuby implementation of Nokogiri `< 1.11.4`, and only if the packaged version of libxml2 is 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.


### Mitigation

Upgrade to Nokogiri `>= 1.11.4`.


### Impact

I've done a brief analysis of the published CVEs that are addressed in this upstream release. The libxml2 maintainers have not released a canonical set of CVEs, and so this list is pieced together from secondary sources and may be incomplete.

All information below is sourced from [security.archlinux.org](https://security.archlinux.org), which appears to have the most up-to-date information as of this analysis.

#### [CVE-2019-20388](https://security.archlinux.org/CVE-2019-20388)

- **Severity**: Medium
- **Type**: Denial of service
- **Description**: A memory leak was found in the xmlSchemaValidateStream function of libxml2. Applications that use this library may be vulnerable to memory not being freed leading to a denial of service.
- **Fixed**: https://gitlab.gnome.org/GNOME/libxml2/commit/7ffcd44d7e6c46704f8af0321d9314cd26e0e18a

Verified that the fix commit first appears in v2.9.11. It seems possible that this issue would be present in programs using Nokogiri < v1.11.4.


#### [CVE-2020-7595](https://security.archlinux.org/CVE-2020-7595)

- **Severity**: Medium
- **Type**: Denial of service
- **Description**: xmlStringLenDecodeEntities in parser.c in libxml2 2.9.10 has an infinite loop in a certain end-of-file situation.
- **Fixed**: https://gitlab.gnome.org/GNOME/libxml2/commit/0e1a49c8907645d2e155f0d89d4d9895ac5112b5

This has been patched in Nokogiri since v1.10.8 (see #1992).


#### [CVE-2020-24977](https://security.archlinux.org/CVE-2020-24977)

- **Severity**: Medium
- **Type**: Information disclosure
- **Description**: GNOME project libxml2 <= 2.9.10 has a global buffer over-read vulnerability in xmlEncodeEntitiesInternal at libxml2/entitie