How severe is CVE-2009-3724?

CVE-2009-3724 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2009-3724?

CVE-2009-3724 affects the following packages: markdown2 (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2009-3724?

Update markdown2 to 1.0.1.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-3724 is resolved across your whole dependency graph.

How do I detect CVE-2009-3724 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2009-3724 if there is no patch (or I can't update yet)?

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.

Is CVE-2009-3724 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2009-3724, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2009-3724?

CVE-2009-3724 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 56th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2009-3724?

CVE-2009-3724 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2009-3724 published, and has it been updated?

CVE-2009-3724 was published on April 21, 2022 and was last updated on September 30, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2009-3724 — markdown2

MEDIUM

CVE-2009-3724 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in markdown2. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for markdown2 — see the affected versions and patch details below.

Cross-site scripting in markdown2 for python

Also known asPYSEC-2020-235SNYK-PYTHON-PYRAD-40000

Published

Apr 21, 2022

Updated

Sep 30, 2024

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs56th percentile — riskier than 56% of all scored CVEsHighest risk

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

🐍markdown2

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

Description

python-markdown2 before 1.0.1.14 has multiple cross-site scripting (XSS) issues.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`markdown2`	all versions	1.0.1.14`pip install --upgrade 'markdown2==1.0.1.14'`

Affected Products

1 product · 1 configurations

Application

python-markdown2python-markdown2_project

< 1.0.1.14

range

Exploits & PoCs

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

python-markdown2 before 1.0.1.14 has multiple cross-site scripting (XSS)…

openwall.comNVDJan 2020

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for markdown2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update markdown2 to 1.0.1.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-3724 is resolved across your whole dependency graph.
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

python-markdown2 before 1.0.1.14 has multiple cross-site scripting (XSS) issues.

O3 Security · Impact-Aware SCA

Is CVE-2009-3724 in your dependencies?

Find it across PyPI, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

Timeline

First exploit

Jan 16, 2020

Disclosed

Apr 21, 2022

Last updated

Sep 30, 2024

Identifiers

CVE-2009-3724

PYSEC-2020-235

SNYK-PYTHON-PYRAD-40000

References

Advisorynvd.nist.gov · CVE 2009 3724 Advisorygithub.com · GHSA 72cx 5ff9 4hhc Webgithub.com · PYSEC 2020 235.yaml Websnyk.io · SNYK PYTHON PYRAD 40000 Webopenwall.com Packagegithub.com · python markdown2

Related vulnerabilities

Also affects markdown2

This CVE is medium severity; 3 of 3 other CVEs affecting markdown2 are rated as high or higher (top: high).

CVE-2021-26813CVE-2020-11888CVE-2018-5773

Same weakness: CWE-79

This CVE is medium severity; 3 of 5 other CVEs with CWE-79 are rated as high or higher (top: high).

CVE-2026-126075CVE-2026-126063CVE-2026-110802CVE-2026-123364CVE-2026-118670Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedSep 30, 2024