CVE-2026-8161: multiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-8161 is a high-severity flaw (CVSS 7.5) affecting multiparty. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 acc

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-248, CWE-1321
Published	2026-05-12
Last modified	2026-06-17

Publisher (CNA): openjs · Vendor: pillarjs

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-12 10:16 UTCPublished CVE record published
2026-06-17 11:03 UTCUpdated Record last modified

pillarjs multiparty UPGRADE

Affected: < 4.3.0

Fixed in: 4.3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls multiparty

2. UPGRADE to 4.3.0

npm install multiparty@">=4.3.0"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-8161?

multiparty: upgrade to 4.3.0. Exact commands for each OS are on this page.

Is CVE-2026-8161 being exploited?

CVE-2026-8161 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-8161 affect?

CVE-2026-8161 affects multiparty. Severity is high (CVSS 7.5). 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__, construc

How urgent is CVE-2026-8161?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-8162 HIGH 7.5 UPGRADE multiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception
CVE-2026-8159 HIGH 7.5 UPGRADE multiparty@4.2.3 and lower versions are vulnerable to denial of service via regular expression backtracking in

References

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