Vulnerability · Published Aug 30, 2026 · Assigned by EEF
CVE-2026-81318Distinct-query aggregate drops the tenant schema prefix, leaking across tenants in AshSql
Low 2.1
In plain English
A low-severity incorrect authorization in ash_sql from ash-project. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| ash-project | ash_sql | 0.1.0 – before 0.7.1 |
| ash-project | ash_sql | dd092ed273dec7bd2194352f24a39229fc8ae68b – before 3d95478cc9e1d5bfaf6144fe9b9793f29e5ab889 |
Weakness: CWE-863 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/ash-project/ash_sql/security/advisories/GHSA-ww8j-58rc-f8h3 vendor-advisory, related
- https://cna.erlef.org/cves/CVE-2026-81318.html related
- https://osv.dev/vulnerability/EEF-CVE-2026-81318 related
- https://github.com/ash-project/ash_sql/commit/3d95478cc9e1d5bfaf6144fe9b9793f29e5ab889 patch