CVE-2026-5079
CVE-2026-5079 · multer vulnerable to Denial of Service via deeply nested field names
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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 7.5 · High · EPSS 0.5% · Fix available
- Published
- Updated
Stack: node
Affected products and versions
multer
- Versions
- ≥ 1.0.0, < 2.2.0: Affected (semver)
- 2.2.0: Not affected (semver)
- ≥ 3.0.0-alpha.1, < 3.0.0-alpha.2: Affected (semver)
- 3.0.0-alpha.2: Not affected (semver)
Update to 2.2.0; Update to 3.0.0-alpha.2
multer npm
- Affected ranges
- SEMVER: ≥ 1.0.0, < 2.2.0
Update to 2.2.0
multer npm
- Affected ranges
- SEMVER: ≥ 3.0.0-alpha.1, < 3.0.0-alpha.2
Update to 3.0.0-alpha.2