# CVE-2026-8469: phenixdigital phoenix_storybook denial of service via atom table exhaustion

Source: https://junglewise.ai/threats/cve-2026-8469-phenixdigital-phoenix-storybook-denial-of-service-via-atom-table  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-20. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-8469 · Severity: high · CVSS 8.2 · Published 2026-05-20

A vulnerability in Phoenix Storybook, a tool used to showcase and test UI components in Elixir applications, allows an unauthenticated attacker to crash the entire server. By sending specially crafted requests to the Storybook interface, an attacker can exhaust the system's memory reserved for internal identifiers (atoms). This results in a complete service outage for the affected application and any other services running on the same server node.

Technologies: [Phenix Digital Phoenix Storybook](https://junglewise.ai/threats/technologies/storybook). Vendors: [Phenix Digital](https://junglewise.ai/threats/vendors/phenix-digital).

## Quick answers

**Is CVE-2026-8469 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8469 being exploited in the wild.

**How severe is CVE-2026-8469?** High severity, with a CVSS score of 8.2, published 20 May 2026.

**Which products and versions are affected?** Phenix Digital Phoenix Storybook >= 0.2.0, < 1.1.0.

**Is there a fix for CVE-2026-8469?** A patch was published on 2026-06-09. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-8469 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-8469?** Check whether you run Phenix Digital Phoenix Storybook at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in `PhoenixStorybook.Story.Playground` and `PhoenixStorybook.ExtraAssignsHelpers` due to the use of `String.to_atom/1` on user-supplied event parameters. Specifically, event handlers like `psb-assign` and `psb-toggle` iterate through client-provided maps and intern keys or values as atoms without validation. In the Erlang VM (BEAM), atoms are not garbage-collected and have a hard limit (default ~1.04M). An unauthenticated remote attacker can reach the Storybook route and send a stream of unique strings to exhaust this table, causing the VM to abort. The issue is fixed in version 1.1.0 by using `String.to_existing_atom/1` or validating against a registry of known attributes.

## Affected products

- phenixdigital phoenix_storybook >= 0.2.0, < 1.1.0

## Identifiers

- CVE-2026-8469
- GHSA-833p-95jq-929q

## Timeline

- 2026-05-20: disclosed
- 2026-06-09: advisory: GitHub Advisory published
- 2026-06-09: patched

## References

- [https://api.github.com/users/PJUllrich](https://api.github.com/users/PJUllrich)
- [https://github.com/PJUllrich](https://github.com/PJUllrich)
- [https://api.github.com/users/PJUllrich/gists%7B/gist_id%7D](https://api.github.com/users/PJUllrich/gists%7B/gist_id%7D)
- [https://api.github.com/users/PJUllrich/repos](https://api.github.com/users/PJUllrich/repos)
- [https://avatars.githubusercontent.com/u/10426523?v=4](https://avatars.githubusercontent.com/u/10426523?v=4)
- [https://api.github.com/users/PJUllrich/events%7B/privacy%7D](https://api.github.com/users/PJUllrich/events%7B/privacy%7D)

## Related threats

- [phenixdigital phoenix_storybook auth bypass in ComponentIframeLive](https://junglewise.ai/threats/cve-2026-47068-phenixdigital-phoenix-storybook-auth-bypass-in)