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A GitHub-reviewed security advisory, not necessarily under active exploitation the way our CISA KEV advisories are, but a real, disclosed vulnerability in an open-source dependency.
Affected packages
Vulnerable: >= 2.0.0, < 2.5.0
Patched in 2.5.0
Details
When multer is configured with an asynchronous fileFilter, a single request can crash the Node.js process. If a request is aborted (for example when one file is rejected) while another file's async fileFilter is still pending, the pending callback later resumes a parsing stream that multer has already torn down. busboy then emits an error on a stream that no longer has an error listener, which Node raises as an unhandled 'error' event, and the process exits. A single unauthenticated request is enough, so any application using multer with an asynchronous fileFilter is affected, regardless of storage engine. Uploads using a synchronous fileFilter are not affected.
Users should upgrade to multer 2.5.0 or later.
Use a synchronous fileFilter.
EPSS, exploit probability
Low0.44%
estimated chance of real-world exploitation in the next 30 days, higher than 37.3% of every CVE FIRST.org scores
Refreshed 10/24/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
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A secure code review or supply chain review finds this before an advisory does.