What is GHSA-qvc2-mg72-jjhx?

## Summary Sanitized DOM trees can be unsafe to serialize when a custom policy allows raw-text elements such as ` ` or ` `. The issue affects DOM trees that are constructed or modified programmatically and then passed through `sanitize_dom()` with a policy that keeps these elements. Text nodes inside ` ` and ` ` are serialized literally, so attacker-controlled text containing the matching closing tag sequence can break out of the raw-text context and inject HTML into the serialized output. The default sanitization policy is not affected because it drops the content

How severe is GHSA-qvc2-mg72-jjhx?

No CVSS score has been assigned to GHSA-qvc2-mg72-jjhx yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-qvc2-mg72-jjhx?

GHSA-qvc2-mg72-jjhx affects the following packages: justhtml (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-qvc2-mg72-jjhx?

Update justhtml to 1.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qvc2-mg72-jjhx is resolved across your whole dependency graph.

How do I detect GHSA-qvc2-mg72-jjhx in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for justhtml. 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.

How do I mitigate GHSA-qvc2-mg72-jjhx if there is no patch (or I can't update yet)?

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.

How does O3 Security protect against GHSA-qvc2-mg72-jjhx?

O3 pinpoints whether GHSA-qvc2-mg72-jjhx is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-qvc2-mg72-jjhx actively exploited in the wild?

No public exploit code has been indexed for GHSA-qvc2-mg72-jjhx 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.

When was GHSA-qvc2-mg72-jjhx published, and has it been updated?

GHSA-qvc2-mg72-jjhx was published on March 18, 2026 and was last updated on March 18, 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

GHSA-qvc2-mg72-jjhx

JustHTML Affected by Mutation XSS via Literal Text Serialization in Raw Text Elements (style/script)

Published

Mar 18, 2026

Updated

Mar 18, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

🐍justhtml

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

Summary

Sanitized DOM trees can be unsafe to serialize when a custom policy allows raw-text elements such as <style> or <script>.

The issue affects DOM trees that are constructed or modified programmatically and then passed through sanitize_dom() with a policy that keeps these elements. Text nodes inside <style> and <script> are serialized literally, so attacker-controlled text containing the matching closing tag sequence can break out of the raw-text context and inject HTML into the serialized output.

The default sanitization policy is not affected because it drops the contents of style and script.

Details

The root cause is in HTML serialization of raw-text elements. In serialize.py, text children of script and style are emitted verbatim:

_LITERAL_TEXT_SERIALIZATION_ELEMENTS = frozenset({"script", "style"})

def _serialize_text_for_parent(text: str | None, parent_name: str | None) -> str:
    if not text:
        return ""
    if parent_name in _LITERAL_TEXT_SERIALIZATION_ELEMENTS:
        return text
    return _escape_text(text)

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`justhtml`	all versions	1.12.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for justhtml. 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.
Fix
Update justhtml to 1.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qvc2-mg72-jjhx is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-qvc2-mg72-jjhx 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 GHSA-qvc2-mg72-jjhx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary Sanitized DOM trees can be unsafe to serialize when a custom policy allows raw-text elements such as `<style>` or `<script>`. The issue affects DOM trees that are constructed or modified programmatically and then passed through `sanitize_dom()` with a policy that keeps these elements. Text nodes inside `<style>` and `<script>` are serialized literally, so attacker-controlled text containing the matching closing tag sequence can break out of the raw-text context and inject HTML into the serialized output. The default sanitization policy is not affected because it drops the content

O3 Security · Impact-Aware SCA

Is GHSA-qvc2-mg72-jjhx in your dependencies?

O3 detects GHSA-qvc2-mg72-jjhx across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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