What’s Vulnerable › Vulnerabilities

CVE-2021-23568: Prototype Pollution

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-01-10 · updated 2026-06-17
• Weakness: CWE-1321

Description

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

Affected products

• extend2: before 1.0.1 — fixed in 1.0.1

How to fix

Upgrade to a fixed version: extend2 1.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/eggjs/extend2/blob/master/index.js%23L50-L60
• https://github.com/eggjs/extend2/commit/aa332a59116c8398976434b57ea477c6823054f8
• https://github.com/eggjs/extend2/pull/2
• https://snyk.io/vuln/SNYK-JS-EXTEND2-2320315
• https://github.com/eggjs/extend2/blob/master/index.js%23L50-L60
• https://github.com/eggjs/extend2/commit/aa332a59116c8398976434b57ea477c6823054f8
• https://github.com/eggjs/extend2/pull/2
• https://snyk.io/vuln/SNYK-JS-EXTEND2-2320315

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