Bug 2525787 (CVE-2026-77037)

Summary: CVE-2026-77037 multer: Multer: Denial of Service via file descriptor leak on aborted uploads
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, dbosanac, dmayorov, dschmidt, gotiwari, ikhan, jcantril, jchui, jhe, jhorak, jlanda, jlledo, jreimann, kshier, ktsao, mdessi, mrizzi, mvyas, nboldt, oaljalju, pantinor, pcattana, psrna, rbobbitt, rhel-process-autobot, rojacob, simaishi, stcannon, tsedmik, watson-tool-maintainers, 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 exploit a file descriptor leak by sending repeated aborted or malformed multipart uploads. This can exhaust system resources, leading to a denial of service (DoS) for the affected application.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2542079, 2542080, 2542082, 2542083, 2542084, 2542078, 2542081, 2542085, 2542086    
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Description OSIDB Bzimport 2026-08-28 22:02:14 UTC 
multer is a middleware for handling multipart/form-data in Node.js. In version 2.2.0, when a disk-backed upload is aborted or truncated before the write stream finishes, multer's disk storage engine removes the visible file but does not close the underlying write file descriptor, leaving a deleted but still open descriptor. A remote attacker able to reach an upload route using the built-in disk storage can send repeated aborted or malformed multipart uploads, each one leaking a file descriptor and retaining disk blocks until the process exits, which can exhaust resources and cause a denial of service. The issue is fixed in multer 2.3.0, which closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed. Upgrade to multer 2.3.0 to remediate.