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💧 Hex

GHSA-j3gg-r6gp-95q2

XSS in HEEx class attributes

Published
Apr 12, 2022
Updated
Mar 13, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected
💧phoenix_html

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

Description

The class attribute was not protected against XSS attacks when using HEEx.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💧Hexphoenix_htmlall versions3.0.4

Detection & mitigation playbook

Open-source dependency
  1. Detect

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

  2. Fix

    Update phoenix_html to 3.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j3gg-r6gp-95q2 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-j3gg-r6gp-95q2 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-j3gg-r6gp-95q2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

The `class` attribute was not protected against XSS attacks when using HEEx.
O3 Security · Impact-Aware SCA

Is GHSA-j3gg-r6gp-95q2 in your dependencies?

O3 detects GHSA-j3gg-r6gp-95q2 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.