Prototype Pollution in jquery-deparam

published 2021-04-23 5 y ago modified 2026-06-17 4 mo ago also GHSA-xg68-chx2-253g , EUVD-2021-1232

cvss: 8.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.1%; EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits: 0; none known

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in jquery-deparam 0.5.1 allows a malicious user to inject properties into Object.prototype.

Exploit prediction

2.07% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/BlackFan/client-side-prototype-pollution/blob/master/pp/jquery-deparam.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.5	AV:N/AC:L/Au:S/C:P/I:P/A:P
GitHub	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
npm	jquery-deparam	<=0.5.3	no fix listed

Affected products

n/a jquery-deparam

Classification

Weakness

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

github.com /BlackFan/client-side-prototype-pollution/blob/master/pp/jquery-deparam.md
web, exploit, third-party-advisory
github.com /RetireJS/retire.js/blob/6da45fcb6a3425e55ee8181b2ac35168879bf086/repository/jsrepository-master.json#L824-L84
web
nvd.nist.gov /vuln/detail/CVE-2021-20087
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary