VULNpocalypse

CVE-2026-8467: Unauthenticated remote code execution via HEEx template injection in phoenix_storybook playground

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

Code Injection vulnerability in phenixdigital phoenix_storybook allows unauthenticated remote code execution via unsanitized attribute value interpolation in HEEx template generation. The psb-assign WebSocket event handler in ‘Elixir.PhoenixStorybook.Story.PlaygroundPreviewLive’:handle_event/3 accepts arbitrary attribute names and values from unauthenticated clients. These values are passed to ‘Elixir.PhoenixStorybook.Helpers.ExtraAssignsHelpers’:handle_set_variation_assign/3, which stores them verbatim. When rendering, ‘Elixir.PhoenixStorybook.Rendering.ComponentRenderer’:attributes_markup/1 interpolates binary attribute values directly into a HEEx template string as name=”<val>” without escaping double quotes or HEEx expression delimiters. An attacker can supply a value containing a closing quote followed by a HEEx expression block (e.g. foo” injected={EXPR} bar=”), which causes EXPR to be treated as an inline Elixir expression. The resulting template is compiled via EEx.compile_string/2 and executed via Code.eval_quoted_with_env/3 with full Kernel imports and no sandbox, giving the attacker arbitrary code execution on the server. This issue affects phoenix_storybook from 0.5.0 before 1.1.0.

Description quoted from the CVE record (assigned by EEF, published 2026-05-20).

Weakness: CWE-94 Improper Control of Generation of Code (‘Code Injection’)

How it can be exploited

Exploitable over the network with low attack complexity only when specific conditions are present needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CISA assessment (SSVC): CISA assesses that a public proof of concept exists. Automatable: yes. Technical impact: total.

Public exploit evidence (Exploit Observer)

Also known as: EUVD-2026-31112, GHSA-55hg-8qxv-qj4p

VEDAS cluster: VEDAS:CRYSTALCHIMERA

Exploit Observer links 2 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (2)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (1)

Vulnerability databases and vendor advisories (7)

Catalogue entries, not exploit evidence.

4 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.021
some chance of attack soon
VEDAS
0.986
strong exploit evidence
On CISA KEV
Not listed
Detection rule
None yet

Who is affected

ProductAffectedNot affected
phenixdigital phoenix_storybookfrom 0.5.0 before 1.1.0Not stated
phenixdigital phoenix_storybook (phenixdigital/phoenix_storybook)from e35379dfe2ef before 56ab8464d437 (git commit)Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: hex phoenix_storybook.

How to fix it

Fixed versions stated in the CVE record: 1.1.0.

Vendor guidance:

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

Advisories on this CVE

References

Vendor advisories and patches

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.