CVE-2026-77063 - multer vulnerable to file size limit bypass via async fileFilter race condition
CVE ID :CVE-2026-77063
Published : Aug. 28, 2026, 10:16 p.m. | 13 minutes ago
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.
Severity: 3.7 | LOW
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Published : Aug. 28, 2026, 10:16 p.m. | 13 minutes ago
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.
Severity: 3.7 | LOW
Visit the link for more details, such as CVSS details, affected products, timeline, and more...