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CRITICAL severity

CVE-2021-23807 — jsonpointer

CRITICALFix: janl/node-jsonpointer@a0345f3

CVE-2021-23807 is a critical-severity (CVSS 9.8) CWE-843 vulnerability in jsonpointer. 2 public exploit references exist, so weaponization risk is real. A fix is available for jsonpointer — see the affected versions and patch details below.

Prototype Pollution in node-jsonpointer

Also known asGHSA-282f-qqgm-c34q
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
2 known
Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk
0.00%1.17%2.33%3.50%0.2%2.7%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-23807 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected
📦jsonpointer📦org.webjars.npm:json-pointer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

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 Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmjsonpointerall versions5.0.0npm install jsonpointer@5.0.0
📦npmorg.webjars.npm:json-pointerall versions5.0.0npm install org.webjars.npm:json-pointer@5.0.0

Affected Products

1 product · 1 configurations
Application
jsonpointerjanl
< 5.0.0
range
Exploits & PoCs
2

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

This affects the package jsonpointer before 5.0.0. A type confusion vuln…

snyk.ioNVDNov 2021

This affects the package jsonpointer before 5.0.0. A type confusion vuln…

snyk.ioNVDNov 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsonpointer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update jsonpointer to 5.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-23807 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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