CVE-2026-5079: high-severity vulnerability in multer
multer vulnerable to Denial of Service via deeply nested field names
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.3%
Impact: multer versions 1.0.0 through 2.1.1 and 3.0.0-alpha.1 are vulnerable to a Denial of Service via deeply nested field names in multipart form data. The append-field dependency parses bracket notation in field names with no limit on nesting depth, allowing an attacker to force allocation of deeply nested object structures that consume CPU and memory. A single HTTP request with a crafted multipart body is sufficient to exploit this.
Patches: Users should upgrade to multer 2.2.0 (2.x line) or 3.0.0-alpha.2 (3.x prerelease) and configure the new limits.fieldNestingDepth option to the minimum depth their application requires.
Workarounds: Set limits.fields to a reasonable value to reduce the number of fields an attacker can send per request. This does not fully mitigate the issue but limits the impact.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
multer · multerRelated CVEs — multer
In the same product, most dangerous first.
CVE-2026-88932MEDIUMmulter vulnerable to Denial of Service via orphaned disk writes on aborted uploadsEPSS 0.5%CVE-2026-77078HIGHmulter vulnerable to Denial of Service via crafted multipart field namesEPSS 0.5%CVE-2026-77037HIGHmulter vulnerable to Denial of Service via file descriptor leak on aborted uploadsEPSS 0.5%CVE-2026-113872HIGHmulter vulnerable to Denial of Service via a pending asynchronous fileFilter after request teardownEPSS 0.4%CVE-2026-82333HIGHmulter vulnerable to Denial of Service via oversized array index in field namesEPSS 0.4%CVE-2026-5038MEDIUMmulter vulnerable to Denial of Service via incomplete cleanup of aborted uploadsEPSS 0.4%