# 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.

- **Severity:** Low 2.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** EEF-CVE-2026-81318, GHSA-ww8j-58rc-f8h3

## 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 (Incorrect Authorization)

## Which versions are affected by CVE-2026-81318?

1 open source package ship an affected version, including ash_sql.


| Package | Ecosystem | 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.

## Is CVE-2026-81318 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-81318 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81318 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-81318 exists.

Affected packages and fixed versions:
- ash_sql (Hex): affected from 0.1.0; fixed in 0.7.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-81318/ (Markdown: https://insights.sbomify.com/CVE-2026-81318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81318
- OSV: https://osv.dev/vulnerability/CVE-2026-81318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81318/
Summaries are generated and may contain mistakes; the official description above is the record.