# CVE-2026-78699

## Summary

- **CVE ID:** CVE-2026-78699
- **Severity:** HIGH
- **CVSS Score:** 7.2 (CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-252
- **Published:** Aug 30, 2026
- **Last Modified:** Sep 1, 2026

## Description

Unchecked Return Value vulnerability in ash-project ash_postgres allows a user who can drive a tenant rename to a name that collides with an existing tenant's schema to have their tenant record repointed at that other tenant's live schema, gaining access to its data.

AshPostgres.MultiTenancy.rename_tenant/3 issues the ALTER SCHEMA ... RENAME TO ... with the non-raising Ecto.Adapters.SQL.query/2, discards its {:ok, _} | {:error, _} result, and unconditionally returns :ok. PostgreSQL rejects the rename when the target schema already exists (and on insufficient privilege or lock timeout), but that failure never reaches the caller. The calling manage_tenant update action therefore sees success and commits the tenant row with the new name, which is the schema of a different existing tenant, so subsequent reads and writes for that tenant run against the other tenant's data.

This issue affects ash_postgres: from 0.25.0 before 2.13.0.

## Affected Products

- ash-project — ash_postgres (0.25.0)
- ash-project — ash_postgres (03510dae24020e302558ef947be7ea874a9ce756)

## References

- [CNA](https://github.com/ash-project/ash_postgres/security/advisories/GHSA-6fqq-j9c4-5766)
- [CNA](https://cna.erlef.org/cves/CVE-2026-78699.html)
- [CNA](https://osv.dev/vulnerability/EEF-CVE-2026-78699)
- [CNA](https://github.com/ash-project/ash_postgres/commit/8544ab15fe45784553c2d2da8ee1a388eee0174b)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.11%
- **EPSS Percentile:** 1.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._