What is CVE-2021-23421?

CVE-2021-23421 is a medium-severity vulnerability in Merge-Change Project, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 5.6/10. Published 2021-08-11.

How severe is CVE-2021-23421?

Medium severity. CVSS v3 base score is 5.6 out of 10.

Prototype Pollution in Merge-Change Project

CVE-2021-23421

All versions of package merge-change are vulnerable to Prototype Pollution via the utils.set function.

Vulnerability class: Prototype Pollution

Published 2021-08-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.011 (65.0th percentile), scored 2026-10-24.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Merge-Change Project
Merge-Change — versions 0

Weakness classification (CWE)

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

References

snyk.io/vuln/SNYK-JS-MERGECHANGE-1310985 (Exploit, Third Party Advisory)
github.com/VladimirShestakov/merge-change/blob/9901f145e06158f284f52de42e6ba5b0… (Broken Link)

Frequently asked questions

What is CVE-2021-23421?: CVE-2021-23421 is a medium-severity vulnerability in Merge-Change Project, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 5.6/10. Published 2021-08-11.
How severe is CVE-2021-23421?: Medium severity. CVSS v3 base score is 5.6 out of 10.