{"id":"CVE-2023-26920","aliases":["CLSA-2026-1781744123","CLSA-2026-1781744124","CLSA-2026-1781744131","DEBIAN-CVE-2023-26920","EUVD-2023-1910","GHSA-793h-6f7r-6qvm","GHSA-x3cc-x39p-42qx","ROOT-APP-NPM-CVE-2023-26920","UBUNTU-CVE-2023-26920"],"status":"published","title":"fast-xml-parser vulnerable to Prototype Pollution through tag or attribute name","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-11","score":0.01152,"percentile":0.67353,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321","CWE-863"],"published":"2021-07-02T08:15:08.59Z","modified":"2026-10-28T02:30:24Z","fixes":[{"ecosystem":"npm","package":"fast-xml-parser","fixed_in":["4.1.2"],"sources":["ghsa"]},{"ecosystem":"Root:npm","package":"@rootio/fast-xml-parser","fixed_in":["3.21.1-root.io.1"],"sources":["osv"]},{"ecosystem":"Root:npm","package":"fast-xml-parser","fixed_in":["3.21.1-aikido.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.1.2"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.19.0-tuxcare.0"},{"fixed":"3.19.0-tuxcare.1"}]}],"versions":["3.19.0"],"bundled":2},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.17.5-tuxcare.0"},{"fixed":"3.17.5-tuxcare.1"}]}],"versions":["3.17.5"],"bundled":2},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.14.0-tuxcare.0"},{"fixed":"3.14.0-tuxcare.1"}]}],"versions":["3.14.0"],"bundled":2},{"source":"osv","ecosystem":"Debian:12","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-10","11.4.0+dfsg2+~cs35.7.26-11","11.4.0+dfsg2+~cs35.7.26-12","11.4.0+dfsg2+~cs35.7.26-13","11.4.0+dfsg2+~cs35.7.26-14","11.4.0+dfsg2+~cs35.7.26-15","11.4.0+dfsg2+~cs35.7.26-16","11.4.0+dfsg2+~cs35.7.26-18","11.4.0+dfsg2+~cs35.7.26-19","11.4.0+dfsg2+~cs35.7.26-20","11.4.0+dfsg2+~cs35.7.26-21","11.4.0+dfsg2+~cs35.7.26-22","11.4.0+dfsg2+~cs35.7.26-7","11.4.0+dfsg2+~cs35.7.26-8","11.4.0+dfsg2+~cs35.7.26-9"]},{"source":"osv","ecosystem":"Debian:13","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-13","11.4.0+dfsg2+~cs35.7.26-14","11.4.0+dfsg2+~cs35.7.26-15","11.4.0+dfsg2+~cs35.7.26-16","11.4.0+dfsg2+~cs35.7.26-18","11.4.0+dfsg2+~cs35.7.26-19","11.4.0+dfsg2+~cs35.7.26-20","11.4.0+dfsg2+~cs35.7.26-21","11.4.0+dfsg2+~cs35.7.26-22"]},{"source":"osv","ecosystem":"Debian:14","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-13","11.4.0+dfsg2+~cs35.7.26-14","11.4.0+dfsg2+~cs35.7.26-15","11.4.0+dfsg2+~cs35.7.26-16","11.4.0+dfsg2+~cs35.7.26-18","11.4.0+dfsg2+~cs35.7.26-19","11.4.0+dfsg2+~cs35.7.26-20","11.4.0+dfsg2+~cs35.7.26-21","11.4.0+dfsg2+~cs35.7.26-22"]},{"source":"osv","ecosystem":"Maven","package":"org.apache.druid:druid-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.21.0"}]}],"versions":["0.14.0-incubating","0.14.1-incubating","0.14.2-incubating","0.15.0-incubating","0.15.1-incubating","0.16.0-incubating","0.16.1-incubating","0.17.0","0.17.1","0.18.0","0.18.1","0.19.0","0.20.0","0.20.1","0.20.2"],"bundled":2},{"source":"osv","ecosystem":"npm","package":"fast-xml-parser","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.1.2"}]}],"bundled":2},{"source":"osv","ecosystem":"Root:npm","package":"@rootio/fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.21.1-root.io.1"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"fast-xml-parser","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.21.1-aikido.1"}]}]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-7ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-10","11.4.0+dfsg2+~cs35.7.26-13ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-18","11.4.0+dfsg2+~cs35.7.26-19"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"node-webfont","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["11.4.0+dfsg2+~cs35.7.26-13ubuntu2","11.4.0+dfsg2+~cs35.7.26-14","11.4.0+dfsg2+~cs35.7.26-15","11.4.0+dfsg2+~cs35.7.26-16build1","11.4.0+dfsg2+~cs35.7.26-18"]}],"products":[{"vendor":"naturalintelligence","product":"fast_xml_parser"}],"references":[{"url":"https://gist.github.com/Sudistark/a5a45bd0804d522a1392cb5023aa7ef7","tags":["x_transferred","Exploit","web","report"]},{"url":"https://github.com/advisories/GHSA-793h-6f7r-6qvm","tags":["x_transferred","Third Party Advisory","advisory"]},{"url":"https://github.com/NaturalIntelligence/fast-xml-parser/commit/2b032a4f799c63d83991e4f992f1c68e4dd05804","tags":["x_transferred","Patch","fix","web","report"]},{"url":"https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-x3cc-x39p-42qx","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-26920","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-x3cc-x39p-42qx"},{"url":"https://lists.apache.org/thread.html/r304dfe56a5dfe1b2d9166b24d2c74ad1c6730338b20aef77a00ed2be%40%3Cannounce.apache.org%3E","tags":["web"]},{"url":"https://lists.apache.org/thread.html/r61aab724cf97d80da7f02d50e9af6de5c7c40dd92dab7518746fbaa2%40%3Cannounce.apache.org%3E","tags":["web"]},{"url":"https://lists.apache.org/thread.html/rc9400a70d0ec5cdb8a3486fc5ddb0b5282961c0b63e764abfbcb9f5d%40%3Cdev.druid.apache.org%3E","tags":["web"]},{"url":"http://www.openwall.com/lists/oss-security/2021/07/02/1","tags":["advisory","web"]},{"url":"http://www.openwall.com/lists/oss-security/2021/09/24/1","tags":["advisory","web"]},{"url":"https://lists.apache.org/thread.html/r29e45561343cc5cf7d3290ee0b0e94e565faab19c20d022df9b5e29c%40%3Cdev.druid.apache.org%3E","tags":["advisory","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/26xxx/CVE-2023-26920.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2023-26920","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-26920","tags":["advisory"]},{"url":"https://lists.apache.org/thread.html/r304dfe56a5dfe1b2d9166b24d2c74ad1c6730338b20aef77a00ed2be@%3Cannounce.apache.org%3E","tags":["web"]},{"url":"https://lists.apache.org/thread.html/r61aab724cf97d80da7f02d50e9af6de5c7c40dd92dab7518746fbaa2@%3Cannounce.apache.org%3E","tags":["web"]},{"url":"https://lists.apache.org/thread.html/rc9400a70d0ec5cdb8a3486fc5ddb0b5282961c0b63e764abfbcb9f5d@%3Cdev.druid.apache.org%3E","tags":["web"]},{"url":"https://github.com/NaturalIntelligence/fast-xml-parser","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2023-26920","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-26920","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2023-26920","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T00:00:00Z","modified":"2024-08-02T12:01:31.939Z","updated_at":"2026-11-02T14:35:15.434947Z"}],"euvd":[{"id":"EUVD-2023-1910","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T00:00:00Z","modified":"2024-08-02T12:01:31Z","updated_at":"2026-11-03T03:50:06.766939Z"}],"ghsa":[{"id":"GHSA-x3cc-x39p-42qx","title":"fast-xml-parser vulnerable to Prototype Pollution through tag or attribute name","description":"### Impact\nAs a part of this vulnerability, user was able to se code using `__proto__` as a tag or attribute name.\n\n```js\nconst { XMLParser, XMLBuilder, XMLValidator} = require(\"fast-xml-parser\");\n\nlet XMLdata = \"\u003c__proto__\u003e\u003cpolluted\u003ehacked\u003c/polluted\u003e\u003c/__proto__\u003e\"\n\nconst parser = new XMLParser();\nlet jObj = parser.parse(XMLdata);\n\nconsole.log(jObj.polluted) // should return hacked\n``` \n\n### Patches\nThe problem has been patched in v4.1.2\n\n### Workarounds\nUser can check for \"__proto__\" in the XML string before parsing it to the parser.\n\n### References\nhttps://gist.github.com/Sudistark/a5a45bd0804d522a1392cb5023aa7ef7\n","status":"published","published":"2023-06-13T12:44:34Z","modified":"2023-12-14T22:27:59Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:37:26.012325Z"}],"nvd":[{"id":"CVE-2023-26920","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T17:15:07.72Z","modified":"2026-06-17T05:43:57.063Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:08:54.010507Z"}],"osv":[{"id":"CVE-2021-26920","description":"In the Druid ingestion system, the InputSource is used for reading data from a certain data source. However, the HTTP InputSource allows authenticated users to read data from other sources than intended, such as the local file system, with the privileges of the Druid server process. This is not an elevation of privilege when users access Druid directly, since Druid also provides the Local InputSource, which allows the same level of access. But it is problematic when users interact with Druid indirectly through an application that allows users to specify the HTTP InputSource, but not the Local InputSource. In this case, users could bypass the application-level restriction by passing a file URL to the HTTP InputSource.","status":"published","published":"2021-07-02T08:15:08.59Z","modified":"2026-10-24T10:31:03.878819841Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:44:18.778776Z"},{"id":"DEBIAN-CVE-2023-26920","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T17:15:07.72Z","modified":"2026-10-26T18:00:41.442865684Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:39.679062Z"},{"id":"GHSA-793h-6f7r-6qvm","title":"Druid ingestion system Authenticated users can read data from other sources than intended","description":"In the Druid ingestion system, the InputSource is used for reading data from a certain data source. However, the HTTP InputSource allows authenticated users to read data from other sources than intended, such as the local file system, with the privileges of the Druid server process. This is not an elevation of privilege when users access Druid directly, since Druid also provides the Local InputSource, which allows the same level of access. But it is problematic when users interact with Druid indirectly through an application that allows users to specify the HTTP InputSource, but not the Local InputSource. In this case, users could bypass the application-level restriction by passing a file URL to the HTTP InputSource.","status":"published","published":"2021-08-13T15:21:50Z","modified":"2026-07-08T06:53:00.349295664Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:46:40.657155Z"},{"id":"GHSA-x3cc-x39p-42qx","title":"fast-xml-parser vulnerable to Prototype Pollution through tag or attribute name","description":"### Impact\nAs a part of this vulnerability, user was able to se code using `__proto__` as a tag or attribute name.\n\n```js\nconst { XMLParser, XMLBuilder, XMLValidator} = require(\"fast-xml-parser\");\n\nlet XMLdata = \"\u003c__proto__\u003e\u003cpolluted\u003ehacked\u003c/polluted\u003e\u003c/__proto__\u003e\"\n\nconst parser = new XMLParser();\nlet jObj = parser.parse(XMLdata);\n\nconsole.log(jObj.polluted) // should return hacked\n``` \n\n### Patches\nThe problem has been patched in v4.1.2\n\n### Workarounds\nUser can check for \"__proto__\" in the XML string before parsing it to the parser.\n\n### References\nhttps://gist.github.com/Sudistark/a5a45bd0804d522a1392cb5023aa7ef7\n","status":"published","published":"2023-06-13T12:44:34Z","modified":"2026-07-08T06:49:36.622686398Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:59.484835Z"},{"id":"UBUNTU-CVE-2023-26920","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T17:15:00Z","modified":"2026-10-17T12:57:16.224347046Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T16:54:20.198616Z"},{"id":"CLSA-2026-1781744123","title":"TuxCare security update for fast-xml-parser (2 CVEs)","description":"TuxCare rebuilt fast-xml-parser to address 2 CVEs. Fixed in 3.19.0-tuxcare.1.","status":"published","published":"2026-08-04T14:52:38Z","modified":"2026-10-15T09:45:56.500939866Z","updated_at":"2026-11-02T15:43:45.794021Z"},{"id":"CLSA-2026-1781744124","title":"TuxCare security update for fast-xml-parser (2 CVEs)","description":"TuxCare rebuilt fast-xml-parser to address 2 CVEs. Fixed in 3.17.5-tuxcare.1.","status":"published","published":"2026-08-04T14:52:38Z","modified":"2026-10-15T09:47:08.112922321Z","updated_at":"2026-11-02T15:43:45.794021Z"},{"id":"CLSA-2026-1781744131","title":"TuxCare security update for fast-xml-parser (2 CVEs)","description":"TuxCare rebuilt fast-xml-parser to address 2 CVEs. Fixed in 3.14.0-tuxcare.1.","status":"published","published":"2026-08-04T14:52:38Z","modified":"2026-10-15T09:45:56.497413955Z","updated_at":"2026-11-02T15:43:45.794021Z"},{"id":"CVE-2023-26920","description":"fast-xml-parser before 4.1.2 allows __proto__ for Prototype Pollution.","status":"published","published":"2023-12-12T00:00:00Z","modified":"2026-10-28T02:30:24.345109022Z","updated_at":"2026-11-02T15:44:31.135751Z"},{"id":"ROOT-APP-NPM-CVE-2023-26920","title":"CVE-2023-26920 in @rootio/fast-xml-parser - Patched by Root","description":"Root has patched CVE-2023-26920 in the @rootio/fast-xml-parser package for Root:npm. Multiple fixed versions available.","status":"published","published":"2026-06-30T07:39:47Z","modified":"2026-06-30T13:15:06.100196874Z","updated_at":"2026-11-02T15:53:27.362922Z"}]}}