CVE-2026-8469 Unauthenticated denial-of-service via BEAM atom table exhaustion in phoenix_storybook
Unauthenticated attackers can crash the BEAM node by exhausting the atom table via unvalidated string-to-atom conversions in phoenix_storybook.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-8469?
CVE-2026-8469 is a high-severity denial of service vulnerability in phenixdigital phoenix_storybook, published on 20 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Allocation of Resources Without Limits or Throttling vulnerability in phenixdigital phoenix_storybook allows unauthenticated denial-of-service via BEAM atom table exhaustion.
Multiple LiveView event handlers convert user-supplied event parameter strings to atoms using String.to_atom/1 without validation: 'Elixir.PhoenixStorybook.ExtraAssignsHelpers':handle_set_variation_assign/3 interns every key of the psb-assign params map; 'Elixir.PhoenixStorybook.ExtraAssignsHelpers':handle_toggle_variation_assign/3 interns the "attr" value from psb-toggle events; 'Elixir.PhoenixStorybook.ExtraAssignsHelpers':to_variation_id/2 interns elements of "variation_id"; and 'Elixir.PhoenixStorybook.ExtraAssignsHelpers':to_value/4 interns raw string values for attributes declared as :atom or :boolean. BEAM atoms are never garbage-collected, so each unique attacker-controlled string is a permanent allocation. Once the atom table ceiling (~1,048,576 atoms) is reached, the entire BEAM node aborts, taking down all applications running on it.
This issue affects phoenix_storybook from 0.2.0 before 1.1.0.
Weakness: CWE-770
Which versions are affected by CVE-2026-8469?
3 open source packages ship an affected version, including phoenix_storybook.
| Package | Affected | Fixed in |
|---|---|---|
phoenix_storybook Hex | From 0.2.0 | 1.1.0 |
phoenix_storybook Hex | From 0.2.0 | 1.1.0 |
phoenix_storybook Hex | From 0.2.0 | 1.1.0 |
How do I fix CVE-2026-8469?
Upgrade phoenix_storybook to 1.1.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-8469 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-8469 exists.
Sources
Also known as EEF-CVE-2026-8469, GHSA-833p-95jq-929q.