How severe is GHSA-55hg-8qxv-qj4p?

No CVSS score has been assigned to GHSA-55hg-8qxv-qj4p yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-55hg-8qxv-qj4p?

GHSA-55hg-8qxv-qj4p affects the following packages: phoenix_storybook (Hex). Ecosystems affected: Hex.

How do I fix GHSA-55hg-8qxv-qj4p?

Update phoenix_storybook to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-55hg-8qxv-qj4p is resolved across your whole dependency graph.

How do I detect GHSA-55hg-8qxv-qj4p in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phoenix_storybook. 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-55hg-8qxv-qj4p 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-55hg-8qxv-qj4p?

O3 pinpoints whether GHSA-55hg-8qxv-qj4p 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-55hg-8qxv-qj4p actively exploited in the wild?

No public exploit code has been indexed for GHSA-55hg-8qxv-qj4p 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-55hg-8qxv-qj4p?

GHSA-55hg-8qxv-qj4p has an EPSS (Exploit Prediction Scoring System) score of 0.9%, placing it in the 56th 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-55hg-8qxv-qj4p?

GHSA-55hg-8qxv-qj4p is classified as Code Injection (CWE-94). 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-55hg-8qxv-qj4p published, and has it been updated?

GHSA-55hg-8qxv-qj4p was published on June 9, 2026 and was last updated on June 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💧 Hex

GHSA-55hg-8qxv-qj4p

PhoenixStorybook: Unauthenticated remote code execution via HEEx template injection in phoenix_storybook playground

Also known asCVE-2026-8467EEF-CVE-2026-8467

Published

Jun 9, 2026

Updated

Jun 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.9%probability of exploitation in next 30 days

Lower Risk56th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

💧phoenix_storybook

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

Summary

An unsafe HEEx template generation vulnerability allows any unauthenticated user to execute arbitrary code on the server. The phoenix_storybook playground accepts user-controlled attribute values over WebSocket and interpolates them unsanitized into a HEEx template that is subsequently compiled and evaluated with full Elixir Kernel access.

Details

The vulnerability is a three-step chain:

1. Unsanitized WebSocket input (extra_assigns_helpers.ex) The psb-assign event handler in PhoenixStorybook.Story.PlaygroundPreviewLive accepts arbitrary attribute names and values from unauthenticated WebSocket clients and stores them verbatim via ExtraAssignsHelpers.handle_set_variation_assign/3.

2. Unescaped interpolation into HEEx (component_renderer.ex) ComponentRenderer.attributes_markup/1 builds a HEEx template string by interpolating binary attribute values directly:

{name, val} when is_binary(val) ->
  ~s|#{name}="#{val}"|

No escaping of " or { is performed. A value such as foo" injected={EXPR} bar=" breaks out of the attribute string and injects EXPR as an inline HEEx expression.

3. Unsandboxed evaluation (component_renderer.ex) The resulting HEEx string is compiled via EEx.compile_string/2 and evaluated via Code.eval_quoted_with_env/3 with full Kernel imports and no sandbox. The injected expression executes on the server even if it causes a rendering error.

PoC

Identify any story URL with a Playground tab (e.g. /storybook/core_components/button).
Connect to the Phoenix LiveView WebSocket without any authentication.
Join the story's LiveView channel and send a psb-assign event with an attribute value that escapes the HEEx attribute context and embeds an Elixir expression (e.g. a System.cmd/2 call).
The server evaluates the injected expression and returns its output in the rendered response.

No authentication, no special configuration, and no user interaction are required.

Impact

This is a pre-authentication remote code execution vulnerability. Any user able to reach the storybook endpoint, including unauthenticated internet users if the storybook is publicly deployed, can execute arbitrary operating system commands with the privileges of the server process. All versions of phoenix_storybook from 0.5.0 before 1.1.0 are affected.

Resources

Introduction Commit: https://github.com/phenixdigital/phoenix_storybook/commit/e35379dfe2ef1a71b141899e36f431017c55265d
Patch Commit: https://github.com/phenixdigital/phoenix_storybook/commit/56ab8464d4375fa52db806148a06cce126ad481d

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`phoenix_storybook`	≥ 0.5.0&&< 1.1.0	1.1.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phoenix_storybook. 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 phoenix_storybook to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-55hg-8qxv-qj4p 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-55hg-8qxv-qj4p 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-55hg-8qxv-qj4p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary An unsafe HEEx template generation vulnerability allows any unauthenticated user to execute arbitrary code on the server. The phoenix_storybook playground accepts user-controlled attribute values over WebSocket and interpolates them unsanitized into a HEEx template that is subsequently compiled and evaluated with full Elixir `Kernel` access. ### Details The vulnerability is a three-step chain: **1. Unsanitized WebSocket input (`extra_assigns_helpers.ex`)** The `psb-assign` event handler in `PhoenixStorybook.Story.PlaygroundPreviewLive` accepts arbitrary attribute names and values

O3 Security · Impact-Aware SCA

Is GHSA-55hg-8qxv-qj4p in your dependencies?

O3 detects GHSA-55hg-8qxv-qj4p across Hex 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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