{"cve":"CVE-2026-77063","nvd":{"published":"2026-08-28T22:16:53.760","modified":"2026-09-02T14:46:51.367","status":"Analyzed","description":"multer is a middleware for handling multipart/form-data in Node.js. When an application uses an asynchronous fileFilter together with the fileSize limit, a race condition in multer's file stream handling can allow a file that exceeds the configured size limit to bypass the size-limit rejection. All versions before 2.3.0 are affected. The impact is limited because the underlying multipart parser still truncates the stream at the size limit, so this is a bypass of the limit rejection rather than uncontrolled resource consumption. The issue is fixed in multer 2.3.0. Upgrade to multer 2.3.0 to remediate.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7},"cwes":["CWE-362"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/expressjs/multer/security/advisories/GHSA-qvfw-j98x-7q72"],"products":["expressjs:multer"],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-77063","score":0.00233,"percentile":0.14282,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-qvfw-j98x-7q72","url":"https://osv.dev/vulnerability/GHSA-qvfw-j98x-7q72","summary":"multer vulnerable to file size limit bypass via async fileFilter race condition","modified":"2026-09-08T21:45:04.622654725Z","packages":[{"ecosystem":"npm","name":"multer","purl":"pkg:npm/multer","ranges":["<2.3.0"],"fixed":["2.3.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}