CVE-2026-76236: stigmem before 0.9.0a12 Cross-Tenant BOLA via Tombstones
stigmem-node before 0.9.0a12 contains a cross-tenant broken object level authorization (BOLA) flaw in the RTBF (right-to-be-forgotten) tombstone mechanism. issuetombstone defaulted the tenant to "default" instead of the caller's tenant, allowing deletion records to be written to the wrong tenant, and the read-suppression path (gettombstonefilter and the tombstone scope cache) lacked a tenantid predicate, so tombstone suppression was applied tenant-blind across fact queries and provenance reads. As a result, a tenant's deletion could be attributed to the wrong tenant and tombstone suppression could either hide facts belonging to other tenants or fail to hide facts within the correct tenant, undermining data isolation and RTBF guarantees. The issue is exploitable only on multi-tenant deployments running the opt-in stigmem-plugin-multi-tenant; single-tenant deployments are unaffected. Fixed in 0.9.0a12.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
stigmemto a version that resolves this vulnerability.Fixed in 0.9.0a12 - Configuration
If you do not require multi-tenant RTBF tombstone behavior, disable the opt-in stigmem-plugin-multi-tenant to avoid the exploitable multi-tenant Cross-Tenant BOLA tombstone issue.
stigmem-plugin-multi-tenant (opt-in) enabled = false
Event History
Frequently Asked Questions
Which deployments are affected?
Only multi-tenant deployments using the opt-in stigmem-plugin-multi-tenant are affected. Single-tenant deployments are unaffected.
What conditions are needed for exploitation?
An attacker needs access to a vulnerable multi-tenant deployment and must be able to use the RTBF tombstone mechanism. The flaw can cause deletion records and tombstone suppression to be applied without correctly scoping them to the caller's tenant.
What is the practical impact on tenant data?
Tombstone suppression may hide facts or provenance data belonging to another tenant, or may fail to suppress data in the correct tenant. This can undermine tenant isolation and RTBF deletion guarantees.
What version fixes the issue?
The issue is fixed in stigmem-node 0.9.0a12. Versions before 0.9.0a12 are affected when used in the vulnerable multi-tenant configuration.