CVE-2019-13118 is a medium-severity (CVSS 5.3) CWE-843 vulnerability in nokogiri. A fix is available for nokogiri — see the affected versions and patch details below.
libxslt Type Confusion vulnerability that affects Nokogiri
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2019-13118.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
nokogiriReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
In numbers.c in libxslt 1.1.33, a type holding grouping characters of an xsl:number instruction was too narrow and an invalid character/length combination could be passed to xsltNumberFormatDecimal, leading to a read of uninitialized stack data.
Nokogiri prior to version 1.10.5 used a vulnerable version of libxslt. Nokogiri 1.10.5 updated libxslt to version 1.1.34 to address this and other vulnerabilities in libxslt.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | nokogiri | all versions | 1.10.5bundle update nokogiri --conservative |
Affected Products
icloudappleiphone osappleitunesapplemac os xapplemacosappletvosappleDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nokogiri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nokogiri to 1.10.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-13118 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2019-13118 in your dependencies?
Find it across RubyGems, including transitive dependencies.