CVE-2026-8467
Unauthenticated remote code execution via HEEx template injection in phoenix_storybook playground
- Critical 9.5
Description
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.
Key facts
- Published
- 20 May 2026
- Last changed
- 27 May 2026
- Assigned by
- EEF
- EPSS
- 2.111% likely to be exploited in the next 30 days, higher than 82.098% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: poc; Automatable: yes; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 9.5CVSS 4.0, Criticalfrom the CNA (EEF)
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
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
CAPEC-242 Code Injection (CNA impact statement)
No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| phenixdigital | phoenix_storybook |
|
| phenixdigital | phoenix_storybook |
|
Timeline
- 20 May 2026 Published