Summary
Nokogiri’s CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an XML attribute. If Ruby code had already accessed an attribute child node, Nokogiri::XML::Attr#value= could free the underlying native child node while the wrapper remained reachable through the document node cache. A later use of the freed child node or a Ruby GC mark could dereference an invalid pointer, causing an invalid read and a possible segfault.
Nokogiri 1.19.4 preserves any already-wrapped attribute child nodes before replacing the attribute value.
JRuby is not affected.
Severity
The Nokogiri maintainers have evaluated this as low severity. Reaching it requires an unusual API-usage pattern that does not arise during normal use. The application must directly access an attribute's child node and then replace that same attribute's value via Attr#value= or #content=. Nokogiri 1.19.4 makes this pattern safe with no change to the public API. Already-wrapped attribute child nodes are preserved before the value is replaced.
Mitigation
Upgrade to Nokogiri 1.19.4 or later.
As a workaround, avoid accessing attribute child nodes directly via Attr#child or similar before mutating the same attribute’s value.
Credit
This issue was responsibly reported by Zheng Yu from depthfirst.com.
Impact
Memory is accessed after it has been freed, leading to undefined behavior in native code. Typical impact: memory corruption, crash, or potential code execution.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-PHWJ-RPRQ-35PP? GHSA-PHWJ-RPRQ-35PP is a low-severity use after free vulnerability in nokogiri (rubygems), affecting versions < 1.19.4. It is fixed in 1.19.4. Memory is accessed after it has been freed, leading to undefined behavior in native code.
- Which versions of nokogiri are affected by GHSA-PHWJ-RPRQ-35PP? nokogiri (rubygems) versions < 1.19.4 is affected.
- Is there a fix for GHSA-PHWJ-RPRQ-35PP? Yes. GHSA-PHWJ-RPRQ-35PP is fixed in 1.19.4. Upgrade to this version or later.
- Is GHSA-PHWJ-RPRQ-35PP exploitable, and should I be worried? Whether GHSA-PHWJ-RPRQ-35PP is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-PHWJ-RPRQ-35PP is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-PHWJ-RPRQ-35PP? Upgrade
nokogirito 1.19.4 or later.