{"id":"GHSA-72gw-mp4g-v24j","summary":"Multer vulnerable to Denial of Service via deeply nested field names","details":"### Impact\n\nMulter is vulnerable to a Denial of Service (DoS) via deeply nested field names in multipart form data. The `append-field` dependency parses bracket notation in field names (e.g., `a[b][c]`) with no limit on nesting depth, allowing an attacker to force allocation of deeply nested object structures that consume CPU and memory. A single HTTP request with a crafted multipart body is sufficient to exploit this.\n\n### Patches\n\nUsers should upgrade to `2.2.0` and configure `limits.fieldNestingDepth` to the minimum depth their application requires.\n\n### Workarounds\n\nSet `limits.fields` to a reasonable value to reduce the number of fields an attacker can send per request. This does not fully mitigate the issue but limits the impact.","aliases":["CVE-2026-5079"],"modified":"2026-06-17T18:15:08.114194969Z","published":"2026-06-17T18:12:27Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-06-17T18:12:27Z","nvd_published_at":"2026-06-15T14:16:37Z","cwe_ids":["CWE-400"]},"references":[{"type":"WEB","url":"https://github.com/expressjs/multer/security/advisories/GHSA-72gw-mp4g-v24j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5079"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/expressjs/multer"}],"affected":[{"package":{"name":"multer","ecosystem":"npm","purl":"pkg:npm/multer"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.0.0"},{"fixed":"2.2.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-72gw-mp4g-v24j/GHSA-72gw-mp4g-v24j.json"}},{"package":{"name":"multer","ecosystem":"npm","purl":"pkg:npm/multer"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0-alpha.1"},{"fixed":"3.0.0-alpha.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-72gw-mp4g-v24j/GHSA-72gw-mp4g-v24j.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}