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📦 npm

CVE-2019-9844

MEDIUM

CVE-2019-9844 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in simple-markdown. O3 Security confirms whether CVE-2019-9844 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Cross-Site Scripting in simple-markdown

Also known asGHSA-qj3f-9gmq-fwv5
Published
Apr 9, 2019
Updated
Jul 8, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

simple-markdownnpm
174Kdownloads / week

Description

simple-markdown.js in Khan Academy simple-markdown before 0.4.4 allows XSS via a data: or vbscript: URI.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmsimple-markdownall versions0.4.4

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for simple-markdown. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update simple-markdown to 0.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-9844 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.

  4. How O3 protects you

    O3 pinpoints whether CVE-2019-9844 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2019-9844. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

simple-markdown.js in Khan Academy simple-markdown before 0.4.4 allows XSS via a data: or vbscript: URI.
O3 Security · Impact-Aware SCA

Is CVE-2019-9844 in your dependencies?

O3 detects CVE-2019-9844 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.