{"id":"CVE-2026-56669","aliases":["GHSA-9643-4qgh-g8mx"],"url":"https://o3.security/vulnerability/CVE-2026-56669","summary":"Elysia: Inefficient Algorithmic Complexity and Interpretation Conflict","details":"Elysia v1.4.28 is vulnerable to denial-of-service attacks due to CPU exhaustion in the form data normalization code.\n\nElysia uses `getAll` to retrieve value from FormData. It is called directly relative to the total number of key-value pairs in the form data. The total amount of work the for loop has to do grows quadratically, so doubling the number of unique key-value pairs quadruples the amount of work. In the above PoC, each .getAll call scans through all of the `n` key-value pairs in the form data. Because there are `n` unique keys in the form data, there are .getAll calls, so in total the form data normalizer has to scan `n` x `n` key-value pairs.\n\n### Impact\nEndpoints using `multipart/form-data`\n\n### Patches\n1.4.29\n\n### Workarounds\nno 100% confirm workaround beside updating the patch","published":"2026-07-08T20:25:18.200Z","modified":"2026-10-21T02:58:43.310317196Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"elysia","fixedVersion":"1.4.29"}],"fix":{"url":"https://github.com/elysiajs/elysia/commit/8358ff9efbcedf9534995f5977f26b9ceab59329","label":"elysiajs/elysia@8358ff9"},"references":[{"type":"WEB","url":"https://gist.github.com/jviide/ea040eabe7bac058326174e2cd42dfd9"},{"type":"WEB","url":"https://github.com/elysiajs/elysia/releases/tag/1.4.29"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56669.json"},{"type":"ADVISORY","url":"https://github.com/elysiajs/elysia/security/advisories/GHSA-9643-4qgh-g8mx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56669"},{"type":"FIX","url":"https://github.com/elysiajs/elysia/commit/8358ff9efbcedf9534995f5977f26b9ceab59329"},{"type":"PACKAGE","url":"https://github.com/elysiajs/elysia"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:43.310317196Z"}}