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Description

multiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception. By sending a multipart/form-data request with a field name that collides with an inherited Object.prototype property such as __proto__, constructor, or toString, the parser invokes .push() on the inherited prototype value rather than an array, throwing a TypeError that propagates as an uncaught exception and crashes the process. Impact: any service accepting multipart uploads via multiparty is affected. Workarounds: none. Upgrade to multiparty@4.3.0 or higher.

PUBLISHED Reserved 2026-05-08 | Published 2026-05-12 | Updated 2026-05-12 | Assigner openjs




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-248: Uncaught Exception

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Product status

Default status
unaffected

Any version
affected

4.3.0 (semver)
unaffected

Credits

Ser0n-ath reporter

Sebastian Beltran remediation developer

kq5y finder

Byambadalai Sumiya finder

Blake Embrey remediation reviewer

Ulises Gascón remediation reviewer

References

github.com/...iparty/security/advisories/GHSA-qxch-whhj-8956

cna.openjsf.org/security-advisories.html

cve.org (CVE-2026-8161)

nvd.nist.gov (CVE-2026-8161)

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