How severe is CVE-2009-5065?

CVE-2009-5065 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-2009-5065?

CVE-2009-5065 affects the following packages: feedparser (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2009-5065?

Update feedparser to 5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-5065 is resolved across your whole dependency graph.

How do I detect CVE-2009-5065 in my PyPI dependencies?

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

How do I mitigate CVE-2009-5065 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-2009-5065 actively exploited in the wild?

Yes. There are 4 known exploit references for CVE-2009-5065, including 1 documented proof-of-concept exploit on Exploit-DB and 3 in-the-wild exploitations 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-2009-5065?

CVE-2009-5065 has an EPSS (Exploit Prediction Scoring System) score of 4.5%, placing it in the 92th 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-2009-5065?

CVE-2009-5065 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-2009-5065 published, and has it been updated?

CVE-2009-5065 was published on April 11, 2011 and was last updated on April 10, 2026. 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-2009-5065 — feedparser

MEDIUM

CVE-2009-5065 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in feedparser. 4 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for feedparser — see the affected versions and patch details below.

feedparser Cross-site Scripting vulnerability

Also known asGHSA-3mwg-gp5g-fv3qPYSEC-2011-18

Published

Apr 11, 2011

Updated

Apr 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

4 known

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

EPSS Exploitation Probability

via FIRST.org ↗

4.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs92th percentile — riskier than 92% 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

🐍feedparser

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

Cross-site scripting (XSS) vulnerability in feedparser.py in Universal Feed Parser (aka feedparser or python-feedparser) before 5.0 allows remote attackers to inject arbitrary web script or HTML via vectors involving nested CDATA stanzas.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`feedparser`	all versions	5.0`pip install --upgrade 'feedparser==5.0'`

Affected Products

1 product · 9 configurations

Application

feedparsermark_pilgrim

≤ 4.1

8 versions

3.03.0.13.13.23.34.04.0.14.0.2

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.

EDB-35570remotemultiple✓ Verified

python-feedparser 5.0 - '/feedparser/feedparser.py' Cross-Site Scripting

by fazalmajid · Apr 5, 2011

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for feedparser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update feedparser to 5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2009-5065 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

O3 Security · Impact-Aware SCA

Is CVE-2009-5065 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. 4 public proof-of-concept references are listed on this page.

Timeline

First exploit

Apr 5, 2011

Disclosed

Apr 11, 2011

Last updated

Apr 10, 2026

Identifiers

CVE-2009-5065

GHSA-3mwg-gp5g-fv3q

PYSEC-2011-18

References

Advisorysecunia.com Advisorymandriva.com · advisories Advisorynvd.nist.gov · CVE 2009 5065 Advisorygithub.com · GHSA 3mwg gp5g fv3q Weblists.opensuse.org · msg00026 Websupport.novell.com · CVE 2009 5065 Websecurityfocus.com Webgithub.com · PYSEC 2011 18.yaml Webweb.archive.org Webweb.archive.org · advisories Packagegithub.com · feedparser Evidencecode.google.com · detail Evidencebugzilla.novell.com · show bug.cgi Evidencebugzilla.redhat.com · show bug.cgi

Related vulnerabilities

Also affects feedparser

This CVE is medium severity; 4 of 4 other CVEs affecting feedparser are rated as high or higher (top: high).

CVE-2012-2921CVE-2011-1157CVE-2011-1158CVE-2011-1156

Same weakness: CWE-79

This CVE is medium severity; 4 of 4 other CVEs with CWE-79 are rated as high or higher (top: critical).

CVE-2026-55649CVE-2026-113787CVE-2026-44267CVE-2026-96632Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedApr 10, 2026