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CVE-2026-82724 is a CWE-863 vulnerability in ash_phoenix. O3 Security confirms whether CVE-2026-82724 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Broken access control in AshPhoenix SubdomainHook via a nil tenant in handle_subdomain

Also known asGHSA-39c8-xcwr-gqff
Published
Aug 31, 2026
Updated
Aug 31, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Aug 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
💧ash_phoenix

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.

Description

Summary

Incorrect Authorization vulnerability in ash-project ash_phoenix invokes the SubdomainHook authorization callback with a nil tenant, so tenant-scoped access checks never see the tenant they are meant to enforce.

AshPhoenix.LiveView.SubdomainHook.on_mount/4 attached a handle_params hook to assign the tenant and then immediately called handle_subdomain in the same on_mount. The tenant assign is only written when LiveView later runs handle_params, strictly after on_mount returns, so handle_subdomain read an unset assign and ran as apply(m, f, [socket, nil | a]). A consumer gate that halts when the user does not belong to the tenant instead evaluated nil, either crashing or taking a permissive branch, and it was never re-run once the real subdomain was assigned or on later navigations. The fix runs handle_subdomain inside the handle_params hook with the real tenant on every navigation.

This issue affects ash_phoenix: from 2.1.26 before 2.3.25.

Configuration

The application uses AshPhoenix.LiveView.SubdomainHook with a handle_subdomain callback as a tenant-scoped authorization gate.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💧Hexash_phoenix2.1.26&&< 2.3.252.3.25

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ash_phoenix. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update ash_phoenix to 2.3.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-82724 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-82724 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-82724. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary Incorrect Authorization vulnerability in ash-project ash\_phoenix invokes the SubdomainHook authorization callback with a nil tenant, so tenant-scoped access checks never see the tenant they are meant to enforce. AshPhoenix.LiveView.SubdomainHook.on\_mount/4 attached a handle\_params hook to assign the tenant and then immediately called handle\_subdomain in the same on\_mount. The tenant assign is only written when LiveView later runs handle\_params, strictly after on\_mount returns, so handle\_subdomain read an unset assign and ran as apply(m, f, \[socket, nil | a\]). A consumer
O3 Security · Impact-Aware SCA

Is CVE-2026-82724 in your dependencies?

O3 detects CVE-2026-82724 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

CVE-2026-82724: ash_phoenix | O3 Security