CVE-2026-8161
HighSummary
Versions of multiparty up to 4.2.3 are vulnerable to denial of service due to an uncaught exception. By sending a multipart/form-data request with a field name that collides with an Object.prototype property, the parser invokes .push() on the inherited prototype value, leading to a TypeError and crashing the process.
Risk Assessment
Any service accepting multipart uploads via multiparty is at risk of crashing. The lack of available workarounds increases the risk of service downtime.
Recommendation
It is recommended to upgrade to multiparty version 4.3.0 or higher to mitigate this vulnerability.
Other vulnerabilities in multiparty
See all- CVE-2026-8162High
Versions of multiparty up to 4.2.3 are vulnerable to denial of service due to an uncaught exception. By sending a multipart/form-data request with a malformed percent-encoding in the Content-Disposition header, the parser invokes decodeURI without error handling, leading to a process crash.
- CVE-2026-8159High
Versions of multiparty up to 4.2.3 are vulnerable to denial of service due to regular expression backtracking in the Content-Disposition filename parameter parser. A crafted multipart upload with a long header value can cause regex matching to take seconds, blocking the event loop.
Original NVD description (English source)
[email protected] 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 [email protected] or higher.