CVE-2021-23807: Prototype Pollution

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-11-03 · updated 2026-06-17
Weakness: CWE-843

Description

This affects the package jsonpointer before 5.0.0. A type confusion vulnerability can lead to a bypass of a previous Prototype Pollution fix when the pointer components are arrays.

Affected products

jsonpointer: before 5.0.0 — fixed in 5.0.0
Npm Jsonpointer: before 5.0.0 — fixed in 5.0.0
Npm Org.Webjars.Npm:Json-Pointer: before 5.0.0 — fixed in 5.0.0

How to fix

Upgrade to a fixed version: jsonpointer 5.0.0; Npm Jsonpointer 5.0.0; Npm Org.Webjars.Npm:Json-Pointer 5.0.0. Check the vendor advisory for mitigations.

References

https://github.com/janl/node-jsonpointer/commit/a0345f3550cd9c4d89f33b126390202b89510ad4
https://github.com/janl/node-jsonpointer/pull/51
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1910273
https://snyk.io/vuln/SNYK-JS-JSONPOINTER-1577288
https://github.com/janl/node-jsonpointer/commit/a0345f3550cd9c4d89f33b126390202b89510ad4
https://github.com/janl/node-jsonpointer/pull/51
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1910273
https://snyk.io/vuln/SNYK-JS-JSONPOINTER-1577288

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