CVE-2026-81318 Distinct-query aggregate drops the tenant schema prefix, leaking across tenants in AshSql
Attackers can read aggregate data from other tenants in AshSql applications using distinct queries due to missing schema prefixes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-81318?
CVE-2026-81318 is a low-severity missing authorization vulnerability in ash-project ash_sql, published on 30 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Incorrect Authorization vulnerability in ash-project ash_sql allows a caller in a schema-based multitenant application to receive aggregate values computed from another tenant's rows.
When an aggregate is computed over a distinct query, AshSql.AggregateQuery.add_single_aggs/5 rebuilds the outer query from query.from.source alone, which is only the {table, schema} tuple and does not carry query.prefix or query.from.prefix. For strategy(:context) multitenancy those hold the tenant schema, so the rebuilt outer query reads the repo's default schema while the inner correlated subquery still reads the tenant schema, and the two are joined only on primary key. The aggregate, and any relationship join added off the prefix-less binding, is then computed against the wrong tenant's rows. The neighbouring limit and exists branches instead wrap the query with subquery/1, which preserves the prefix.
This issue affects ash_sql: from 0.1.0 before 0.7.1.
Weakness: CWE-863
Which versions are affected by CVE-2026-81318?
1 open source package ship an affected version, including ash_sql.
| Package | Affected | Fixed in |
|---|---|---|
ash_sql Hex | From 0.1.0 | 0.7.1 |
How do I fix CVE-2026-81318?
Upgrade ash_sql to 0.7.1 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-81318 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-81318 exists.
Sources
Also known as EEF-CVE-2026-81318, GHSA-ww8j-58rc-f8h3.