Prototype Pollution

published 2021-02-04 5 y ago modified 2026-06-17 4 mo ago also GHSA-j32x-j8pj-pg2h , EUVD-2021-0836

cvss: 8.6; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.8%; EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits: 0; none known

This affects all versions of package decal. The vulnerability is in the extend function.

Exploit prediction

1.78% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

snyk.io https://snyk.io/vuln/SNYK-JS-DECAL-1051028 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub	3.1	8.6	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Affected packages

ecosystem	package	affected	fixed in
npm	decal	<=2.1.3	no fix listed

Affected products

n/a decal

Classification

Weakness

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
CWE-400 Uncontrolled Resource Consumption
CWE-94 Improper Control of Generation of Code

References

snyk.io /vuln/SNYK-JS-DECAL-1051028
web, exploit, third-party-advisory
npmjs.com /package/decal
web, product, third-party-advisory
github.com /gigafied/decal.js/blob/master/src/utils/extend.js%23L23-L56
broken-link
nvd.nist.gov /vuln/detail/CVE-2020-28450
advisory
github.com /gigafied/decal.js/blob/master/src/utils/extend.js#L23-L56
web

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