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CVE-2026-77063

CVE-2026-77063 · multer vulnerable to file size limit bypass via async fileFilter race condition

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 3.7 · Low · EPSS 0.2% · Fix available

Published
Updated

Stack: node

Affected products and versions

  • multer

    Versions
    • ≥ 0, < 2.3.0: Affected (semver)
    • 2.3.0: Not affected (semver)

    Update to 2.3.0

  • multer npm

    Affected ranges
    • SEMVER: < 2.3.0

    Update to 2.3.0

Original sources

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