CVE-2026-77063
lowpriority · track · 0EPSS 0.002 · 13 %ileDEFRUSEPSS · scored 2026-10-23
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (7)
Products and version ranges known to be affected.
- IBM WebSphere Service Registry and Repositoryall versionscert_bundDEcpe:/a:ibm:websphere_service_registry_and_repository:-
advisories (3)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3596IBM App Connect Enterprise: Mehrere SchwachstellenDeutsch2026-09-27csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in IBM App Connect Enterprise ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren und um einen Cross-Site Scripting Angriff durchzuführen.
- GHSA-qvfw-j98x-7q72multer vulnerable to file size limit bypass via async fileFilter race condition2026-09-08ghsa · osvUS
### Impact When `multer` is configured with an asynchronous `fileFilter`, the `limits.fileSize` limit can be bypassed. The `'limit'` event is registered inside the async `fileFilter` callback, so if a file exceeds `limits.fileSize` before that callback runs, the event is missed and the oversized upload is accepted instead of being rejected with a `LIMIT_FILE_SIZE` error. Applications that rely on `limits.fileSize` to reject oversized uploads are affected on all upload methods (`.single()`, `.array()`, `.fields()`, `.any()`). Uploads using a synchronous `fileFilter` are not affected. ### Patches Users should upgrade to `2.3.0`. ### Workarounds Use a synchronous `fileFilter`, or validate the uploaded file size after the upload completes.
- CERTFR-2026-AVI-1378Multiples vulnérabilités dans les produits IBMFrançais2026-10-23vendor · certfrFR
sources
Which sources assert this record, and when.
references (2) nvd
External citations — patches, advisories, analysis.
- https://cna.openjsf.org/security-advisories.htmlVendor Advisory
- https://github.com/expressjs/multer/security/advisories/GHSA-qvfw-j98x-7q72Vendor AdvisoryMitigation
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