GHSA-fj3w-jwp8-x2g3
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
fast-xml-parsernpmDescription
Impact
Application crashes with stack overflow when user use XML builder with prserveOrder:true for following or similar input
[{
'foo': [
{ 'bar': [{ '@_V': 'baz' }] }
]
}]
Cause: arrToStr was not validating if the input is an array or a string and treating all non-array values as text content.
What kind of vulnerability is it? Who is impacted?
Patches
Yes in 5.3.8
Workarounds
Use XML builder with preserveOrder:false or check the input data before passing to builder.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | fast-xml-parser | ≥ 5.0.0&&< 5.3.8 | 5.3.8 |
| 📦npm | fast-xml-parser | ≥ 4.0.0-beta.0&&< 4.5.4 | 4.5.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fast-xml-parser. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update fast-xml-parser to 5.3.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fj3w-jwp8-x2g3 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.
How O3 protects you
O3 pinpoints whether GHSA-fj3w-jwp8-x2g3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-fj3w-jwp8-x2g3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-fj3w-jwp8-x2g3 in your dependencies?
O3 detects GHSA-fj3w-jwp8-x2g3 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.