Log in Start free

Vulnerability · Published Oct 26, 2026 · Assigned by EEF

CVE-2026-96581An upsert on the primary key in Ash ignores attribute multitenancy, so one tenant can read, overwrite and take over another tenant's records

High 7.6

In plain English

A high-severity authorization bypass via user-controlled key in ash from ash-project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities).

Severity (CVSS 4.0)7.6High
Exploit odds (30 days)0.3%top 82.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

VendorProductVersions
ash-project ash 1.22.0 – before 3.37.2
ash-project ash 2333d01ddf37e5909769a513059b27e3183331c5 – before c9f0cdb31e7c084def05f3f5be69dd7bb7721754

Weakness: CWE-639 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

References