CVE-2026-76236

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. issue_tombstone 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 (_get_tombstone_filter and the tombstone scope cache) lacked a tenant_id 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.

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. issue_tombstone 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 (_get_tombstone_filter and the tombstone scope cache) lacked a tenant_id 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.

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. issue_tombstone 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 (_get_tombstone_filter and the tombstone scope cache) lacked a tenant_id 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.

Summary

On a multi-tenant stigmem node, RTBF (right-to-be-forgotten) tombstones were mis-scoped two ways. (1) issue_tombstone defaulted the tenant to "default" instead of the caller's tenant, so tombstones could be written to the wrong tenant. (2) The read-suppression path — _get_tombstone_filter (routes/facts/common.py) and the _tombstone_scope_cache (lifecycle/tombstones.py) — had no tenant_id predicate, so tombstone suppression was applied tenant-blind across fact queries and provenance. Reached via /v1/tombstones and the fact query/provenance read paths.

Impact

Cross-tenant integrity of the RTBF mechanism: a tenant's deletion request could be recorded against the wrong tenant, and tombstone suppression could hide — or fail to hide — facts across tenant boundaries, undermining both data-view correctness and RTBF guarantees.

Affected configurations

This is a cross-tenant break. It is exploitable only on deployments running the opt-in stigmem-plugin-multi-tenant (multiple tenants on one node). A default single-tenant node has only tenant="default" — there is no second tenant to cross — so it is not exploitable on default deployments. The rating is HIGH for the multi-tenant deployments the plugin exists to isolate.

Patches

Fixed in 0.9.0a12 (PR #728): identity.tenant_id is passed from issue_tombstone into create_tombstone (no more "default" fallback); AND tenant_id = ? was added to _get_tombstone_filter and get_tombstone_status; the suppression cache is re-keyed to include tenant; and all four read call sites thread the caller's tenant. A tenant-B tombstone now suppresses only tenant-B facts and is invisible to tenant-A reads.

Workarounds

None other than upgrading to 0.9.0a12. Single-tenant deployments are unaffected.

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. issue_tombstone 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 (_get_tombstone_filter and the tombstone scope cache) lacked a tenant_id 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.

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. issue_tombstone 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 (_get_tombstone_filter and the tombstone scope cache) lacked a tenant_id 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.

Summary

On a multi-tenant stigmem node, RTBF (right-to-be-forgotten) tombstones were mis-scoped two ways. (1) issue_tombstone defaulted the tenant to "default" instead of the caller's tenant, so tombstones could be written to the wrong tenant. (2) The read-suppression path — _get_tombstone_filter (routes/facts/common.py) and the _tombstone_scope_cache (lifecycle/tombstones.py) — had no tenant_id predicate, so tombstone suppression was applied tenant-blind across fact queries and provenance. Reached via /v1/tombstones and the fact query/provenance read paths.

Impact

Cross-tenant integrity of the RTBF mechanism: a tenant's deletion request could be recorded against the wrong tenant, and tombstone suppression could hide — or fail to hide — facts across tenant boundaries, undermining both data-view correctness and RTBF guarantees.

Affected configurations

This is a cross-tenant break. It is exploitable only on deployments running the opt-in stigmem-plugin-multi-tenant (multiple tenants on one node). A default single-tenant node has only tenant="default" — there is no second tenant to cross — so it is not exploitable on default deployments. The rating is HIGH for the multi-tenant deployments the plugin exists to isolate.

Patches

Fixed in 0.9.0a12 (PR #728): identity.tenant_id is passed from issue_tombstone into create_tombstone (no more "default" fallback); AND tenant_id = ? was added to _get_tombstone_filter and get_tombstone_status; the suppression cache is re-keyed to include tenant; and all four read call sites thread the caller's tenant. A tenant-B tombstone now suppresses only tenant-B facts and is invisible to tenant-A reads.

Workarounds

None other than upgrading to 0.9.0a12. Single-tenant deployments are unaffected.