Unauthenticated remote code execution via HEEx template injection in phoenix_storybook playground
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-94.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| phenixdigital | phoenix_storybook | 0.5.0 to before 1.1.0 | 1.1.0 | Patch available | CNA |
| — | phoenix_storybook (Hex) | 0.5.0 to before 1.1.0 | 1.1.0 | Patch available | GHSA-55hg-8qxv-qj4p |
- phoenix_storybook Vendorphenixdigital Affected 0.5.0 to before 1.1.0 Fixed in 1.1.0 Patch available CNA
- phoenix_storybook (Hex) Vendor— Affected 0.5.0 to before 1.1.0 Fixed in 1.1.0 Patch available GHSA-55hg-8qxv-qj4p
CPE names CNA · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:phenixdigital:phoenix_storybook:*:*:*:*:*:*:*:* | — | — | phenixdigital |
- cpe:2.3:a:phenixdigital:phoenix_storybook:*:*:*:*:*:*:*:* Versions — — ·phenixdigital
Remediation
- Fix · CNA phoenix_storybook (phenixdigital) Fixed in 1.1.0
- Fix · GHSA-55hg-8qxv-qj4p phoenix_storybook (Hex) Fixed in 1.1.0 Advisory →
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
phenixdigital phoenix_storybook 1.1.0
3 records Highest priority Priority HIGH 2 HIGH, 1 MEDIUM
Other records, highest priority first
- TI-2026-07438 Unauthenticated denial-of-service via BEAM atom table exhaustion in phoenix_storybookPriority HIGH 75
- TI-2026-34670 Cross-session PubSub topic injection via URL parameter in phoenix_storybookPriority MEDIUM 51
Timeline
- 2026-10-02 Threatist record created from CVE-2026-8467
- 2026-10-03 Alias added: GHSA-55hg-8qxv-qj4p
References
Patch 1
Advisory 2
More phenixdigital vulnerabilities
- TI-2026-07438 Unauthenticated denial-of-service via BEAM atom table exhaustion in phoenix_storybook CVSS 4.0HIGH 8.2
- TI-2026-34670 Cross-session PubSub topic injection via URL parameter in phoenix_storybook CVSS 4.0LOW 2.3
Sources
- CVE-2026-8467 · CVE Program
- CVE-2026-8467 · NVD
- FIRST EPSS
- GHSA-55hg-8qxv-qj4p · GitHub Advisory Database · CC BY 4.0
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