{"id":"CVE-2026-77063","state":"PUBLISHED","title":"multer vulnerable to file size limit bypass via async fileFilter race condition","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.","publishedAt":"2026-08-28T19:54:58.473Z","updatedAt":"2026-08-31T18:40:55.632Z","severity":{"score":3.7,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","source":"openjs"},"assigner":"openjs","products":["multer multer"],"affected":[{"vendor":"multer","product":"multer","packageURL":"pkg:npm/multer","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.3.0","versionType":"semver"},{"version":"2.3.0","status":"unaffected","versionType":"semver"}]}],"references":["https://github.com/expressjs/multer/security/advisories/GHSA-qvfw-j98x-7q72","https://cna.openjsf.org/security-advisories.html"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77063.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77063","state":"PUBLISHED","datePublished":"2026-08-28T19:54:58.473Z","dateUpdated":"2026-08-31T18:40:55.632Z","assignerShortName":"openjs","assignerOrgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateReserved":"2026-08-20T09:59:20.298Z"},"containers":{"cna":{"title":"multer vulnerable to file size limit bypass via async fileFilter race condition","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"multer","product":"multer","packageURL":"pkg:npm/multer","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.3.0","versionType":"semver"},{"version":"2.3.0","status":"unaffected","versionType":"semver"}]}],"references":[{"url":"https://github.com/expressjs/multer/security/advisories/GHSA-qvfw-j98x-7q72"},{"url":"https://cna.openjsf.org/security-advisories.html"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","baseScore":3.7,"baseSeverity":"LOW"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","description":"CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')","type":"CWE"}]}],"providerMetadata":{"shortName":"openjs","orgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateUpdated":"2026-08-28T19:54:58.473Z"},"credits":[{"lang":"en","type":"reporter","value":"ThinkerHao"},{"lang":"en","type":"remediation developer","value":"bjohansebas"},{"lang":"en","type":"remediation reviewer","value":"UlisesGascon"}],"x_generator":{"engine":"cve-kit 1.0.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-31T18:40:40.694908Z","id":"CVE-2026-77063","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-31T18:40:55.632Z"}}]}}}