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MEDIUM severity

CVE-2020-23849 — jsoneditor

MEDIUM

CVE-2020-23849 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in jsoneditor. 1 public exploit reference exists, so weaponization risk is real. A fix is available for jsoneditor — see the affected versions and patch details below.

Cross-site Scripting in jsoneditor

Also known asGHSA-q854-j362-cfq9
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk
0.00%0.40%0.80%1.20%0.3%0.7%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-23849 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

440other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
jsoneditornpm
269Kdownloads / week

Description

Stored XSS was discovered in the tree mode of jsoneditor before 9.0.2 through injecting and executing JavaScript.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmjsoneditorall versions9.0.2npm install jsoneditor@9.0.2

Affected Products

1 product · 1 configurations
Application
jsoneditorjsoneditoronline
≥ 8.6.6 && < 9.0.2
range
Exploits & PoCs
1

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

Stored XSS was discovered in the tree mode of jsoneditor before 9.0.2 th…

github.comNVDJan 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 jsoneditor, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update jsoneditor to 9.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-23849 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Stored XSS was discovered in the tree mode of jsoneditor before 9.0.2 through injecting and executing JavaScript.
O3 Security · Impact-Aware SCA

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CVE-2020-23849: jsoneditor XSS — Fixed in 9.0.2