Bug 2525771 (CVE-2026-77078)

Summary: CVE-2026-77078 multer: Multer: Denial of Service via crafted multipart field names
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abarbaro, akostadi, alizardo, amasferr, dmayorov, dschmidt, ikhan, jchui, jhe, jlanda, jlledo, kshier, ktsao, nboldt, oaljalju, pantinor, psrna, rbobbitt, simaishi, stcannon, tsedmik, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in multer, a Node.js middleware for handling multipart/form-data. A remote attacker can send a small multipart request containing two specially crafted text field names. This can cause an uncaught error that terminates the Node.js process, leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-28 22:01:20 UTC 
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.