CVE-2026-78699 ash-project CVE debrief

Who should care

Organizations using ash_postgres, especially those with multi-tenancy enabled, should assess their exposure to this vulnerability. Those using versions from 0.25.0 to 2.12.0 should prioritize mitigation efforts. Security teams and platform operators should review the vulnerability details and plan for vendor-supported updates or mitigations. Implementing compensating controls for exposed systems and monitoring for suspicious activities can help reduce the risk until remediation is applied. Vulnerability management and security teams should track exceptions and retest remediated assets to ensure the vulnerability is properly addressed. This vulnerability could have significant operational impacts if exploited, making it essential for affected organizations to take prompt action. Additionally, defenders should verify the integrity of their tenant records and schemas to prevent potential data exposure. They should also review relevant monitoring, detection, and logs for exposed assets that need extra review. The CVE record and vendor advisory provide critical information for understanding the vulnerability's scope and severity. Therefore, it is crucial for organizations to review these resources and assign an owner for follow-up actions. By taking these steps, organizations can minimize the risk associated with CVE-2026-78699 and protect their data from potential exploitation. Furthermore, organizations should consider the potential operational impact of this vulnerability on their systems and take proactive measures to mitigate it. This includes reviewing compensating controls, monitoring for suspicious activities, and planning for vendor-supported updates or mitigations. By being proactive, organizations can reduce the likelihood of a successful exploit and minimize the potential damage. In addition, organizations should ensure that their security teams and platform operators are aware of the vulnerability and its potential impacts, and that they have the necessary resources and support to address it effectively. This may involve providing training or additional resources to help them understand the vulnerability and its mitigation. Overall, a comprehensive and

Technical summary

The AshPostgres.MultiTenancy.rename_tenant/3 function in ash_postgres issues an ALTER SCHEMA ... RENAME TO ... with the non-raising Ecto.Adapters.SQL.query/2, discards its {:ok, _} | {:error, _} result, and unconditionally returns :ok. This leads to a situation where a user who can drive a tenant rename to a name that collides with an existing tenant's schema can have their tenant record repointed at that other tenant's live schema, gaining access to its data.

Defensive priority

Organizations using ash_postgres from version 0.25.0 to 2.12.0 should assess their exposure and apply vendor remediation when available.

Recommended defensive actions

• Inventory ash_postgres installations to identify those using versions from 0.25.0 to 2.12.0.
• Apply vendor remediation when available.
• Monitor for suspicious tenant rename activities.
• Implement compensating controls to restrict access to sensitive data.
• Review relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE-2026-78699 issue arises from an unchecked return value vulnerability in ash_postgres, specifically in the AshPostgres.MultiTenancy.rename_tenant/3 function. This function renames a tenant's schema without properly handling the result of the rename operation, leading to potential data exposure if the target schema already exists.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.