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MEDIUM severity

CVE-2021-4103 — vditor

MEDIUMFix: vanessa219/vditor@8d4d088

CVE-2021-4103 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in vditor. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for vditor — see the affected versions and patch details below.

vditor Vulnerable to Cross-site Scripting in SVG events

Also known asGHSA-cxm3-v4mv-6mh8
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk
0.00%0.39%0.78%1.16%0.2%0.7%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

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.

86other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
vditornpm
51Kdownloads / week

Description

vditor does not filter user input in SVG events, leading to XSS

PoC

</a>
<svg><animate onbegin=alert(11) attributeName=x dur=1s>

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmvditorall versions3.8.11npm install vditor@3.8.11

Affected Products

1 product · 1 configurations
Application
vditorb3log
< 1.0.34
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.

Cross-site Scripting (XSS) - Stored in GitHub repository vanessa219/vdit…

huntr.devNVDJan 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update vditor to 3.8.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4103 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

vditor does not filter user input in SVG events, leading to XSS ### PoC ```html </a> <svg><animate onbegin=alert(11) attributeName=x dur=1s> ```
O3 Security · Impact-Aware SCA

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CVE-2021-4103: vditor XSS — Fixed in 3.8.11