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Not in CISA KEV
MEDIUM severity

CVE-2011-3744 — htmlpurifier

MEDIUM

CVE-2011-3744 is a medium-severity (CVSS 5.3) Information Exposure vulnerability in ezyang/htmlpurifier. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

HTML Purifier allows remote attackers to obtain sensitive information

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk
0.00%0.62%1.25%1.87%0.3%1.4%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
🐘ezyang/htmlpurifier

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

Description

HTML Purifier 4.2.0 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by tests/PHPT/Reporter/SimpleTest.php and certain other files.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐘Packagistezyang/htmlpurifierall versionsNo fix

Affected Products

1 product · 1 configurations
Application
html purifierhtmlpurifier
1 version
4.2.0
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.

HTML Purifier 4.2.0 allows remote attackers to obtain sensitive informat…

code.google.comNVDMar 2012

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Remediation status

    The records we use list no patched version of ezyang/htmlpurifier for CVE-2011-3744. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Frequently Asked Questions

HTML Purifier 4.2.0 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by tests/PHPT/Reporter/SimpleTest.php and certain other files.
O3 Security · Impact-Aware SCA

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CVE-2011-3744: htmlpurifier Info Disclosure (Medium 5.3)