CVE-2026-77078

Summary

multer is a middleware for handling multipart/form-data in Node.js. A small multipart request containing two specially crafted text field names can cause an uncaught RangeError (Invalid array length) that terminates the Node.js process. The first field uses a very large numeric array index to allocate a maximum-length sparse array, and a second field then pushes past that length, which throws inside the append-field dependency and is not caught by multer. All versions before 2.3.0 are affected, and the issue is a remotely triggerable denial of service. The issue is fixed in multer 2.3.0. Upgrade to multer 2.3.0 to remediate.

Affected Software

Weaknesses

• CWE-248: CWE-248: Uncaught Exception

References

• https://github.com/expressjs/multer/security/advisories/GHSA-wc9g-mqfw-jrwm
• https://cna.openjsf.org/security-advisories.html

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