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CVE-2026-96581EUVD-2026-109637

An upsert on the primary key in Ash ignores attribute multitenancy, so one tenant can read, overwrite and take over another tenant's records

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.37.2
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

The Ash framework (the Elixir `ash` library, versions from 1.22.0 up to but not including 3.37.2) is affected. An attacker who can use a create action with upserts enabled on a multitenant resource could read, overwrite, and take over records that belong to another tenant, breaking the data isolation between tenants.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

Authorization Bypass Through User-Controlled Key vulnerability in ash-project ash allows a user of one tenant to read, overwrite and take over another tenant's records via an upserting create action. Under attribute multitenancy, Ash.Actions.Create (lib/ash/actions/create/create.ex) and Ash.Actions.Create.Bulk (lib/ash/actions/create/bulk.ex) upserted on the primary key, or on an all_tenants? identity, without scoping the conflicting record to the request's tenant. A caller of a create action with upsert? true that accepts the primary key, supplying a record id from another tenant, updated that record's upsert fields and received all of its attributes in the result. With the default upsert fields the tenant attribute was written too, moving the record into the caller's tenant. Read and update policies do not run for upserts, and tenant-scoped create policies pass because the tenant is the caller's own. This issue affects ash: from 1.22.0 before 3.37.2.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  4. Record last updated

Affected versions

  • ash

    From 1.22.0 · fixed in 3.37.2

  • ash-project/ash

    From 2333d01ddf37e5909769a513059b27e3183331c5 · fixed in c9f0cdb31e7c084def05f3f5be69dd7bb7721754

References 5

GitHub · ash-project/ash

cna.erlef.org

osv.dev