How severe is GHSA-wvhx-q427-fgh3?

No CVSS score has been assigned to GHSA-wvhx-q427-fgh3 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-wvhx-q427-fgh3?

GHSA-wvhx-q427-fgh3 affects the following packages: html-sanitizer (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-wvhx-q427-fgh3?

Update html-sanitizer to 2.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wvhx-q427-fgh3 is resolved across your whole dependency graph.

How do I detect GHSA-wvhx-q427-fgh3 in my PyPI dependencies?

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

How do I mitigate GHSA-wvhx-q427-fgh3 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 GHSA-wvhx-q427-fgh3 actively exploited in the wild?

No public exploit code has been indexed for GHSA-wvhx-q427-fgh3 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-wvhx-q427-fgh3?

GHSA-wvhx-q427-fgh3 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 47th 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 GHSA-wvhx-q427-fgh3?

GHSA-wvhx-q427-fgh3 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 GHSA-wvhx-q427-fgh3 published, and has it been updated?

GHSA-wvhx-q427-fgh3 was published on May 6, 2024 and was last updated on September 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

Arbitrary HTML present after sanitization because of unicode normalizationGHSA-wvhx-q427-fgh3

Fix: matthiask/html-sanitizer@48db42f

GHSA-wvhx-q427-fgh3 is a Cross-site Scripting (XSS) vulnerability in html-sanitizer. A fix is available for html-sanitizer — see the affected versions and patch details below.

Also known asCVE-2024-34078PYSEC-2026-1455

Published

May 6, 2024

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-wvhx-q427-fgh3.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs47th percentile — riskier than 47% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

🐍html-sanitizer

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

Impact

If using keep_typographic_whitespace=False (which is the default), the sanitizer normalizes unicode to the NFKC form at the end. Some unicode characters normalize to chevrons; this allows specially crafted HTML to escape sanitization.

Patches

The problem has been fixed in 2.4.2.

Workarounds

Set keep_typographic_whitespace=True explicitly, or normalize to NFKC yourself earlier.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`html-sanitizer`	all versions	2.4.2`pip install --upgrade 'html-sanitizer==2.4.2'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for html-sanitizer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update html-sanitizer to 2.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wvhx-q427-fgh3 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

### Impact If using `keep_typographic_whitespace=False` (which is the default), the sanitizer normalizes unicode to the NFKC form at the end. Some unicode characters normalize to chevrons; this allows specially crafted HTML to escape sanitization. ### Patches The problem has been fixed in 2.4.2. ### Workarounds Set `keep_typographic_whitespace=True` explicitly, or normalize to NFKC yourself earlier.

O3 Security · Impact-Aware SCA

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