What is CVE-2021-23568?

CVE-2021-23568 is a high-severity vulnerability in Eggjs Extend2, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.3/10. Published 2022-01-10.

How severe is CVE-2021-23568?

High severity. CVSS v3 base score is 7.3 out of 10.

Prototype Pollution in Eggjs Extend2

CVE-2021-23568

The package extend2 before 1.0.1 are vulnerable to Prototype Pollution via the extend function due to unsafe recursive merge.

Vulnerability class: Prototype Pollution

Published 2022-01-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.015 (73.2th percentile), scored 2026-10-24.

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 73.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000

Affected products

Eggjs Extend2
Extend2 — versions unspecified

Weakness classification (CWE)

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

References

snyk.io/vuln/SNYK-JS-EXTEND2-2320315 (Exploit, Third Party Advisory)
github.com/eggjs/extend2/blob/master/index.js#L50-L60 (Broken Link)
github.com/eggjs/extend2/commit/aa332a59116c8398976434b57ea477c6823054f8 (Patch, Third Party Advisory)
github.com/eggjs/extend2/pull/2 (Patch, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-23568?: CVE-2021-23568 is a high-severity vulnerability in Eggjs Extend2, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.3/10. Published 2022-01-10.
How severe is CVE-2021-23568?: High severity. CVSS v3 base score is 7.3 out of 10.