How severe is CVE-2026-76236?

No CVSS score has been assigned to CVE-2026-76236 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-76236?

CVE-2026-76236 affects the following packages: stigmem-node (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-76236?

Update stigmem-node to 0.9.0a12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-76236 is resolved across your whole dependency graph.

How do I detect CVE-2026-76236 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for stigmem-node, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-76236 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-76236 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-76236 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-76236?

CVE-2026-76236 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 30th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-76236?

CVE-2026-76236 is classified as CWE-639 (CWE-639). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-76236 published, and has it been updated?

CVE-2026-76236 was published on August 19, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2026-76236 — stigmem-node

Fix: eidetic-labs/stigmem#728

CVE-2026-76236 is a CWE-639 vulnerability in stigmem-node. A fix is available for stigmem-node — see the affected versions and patch details below.

stigmem before 0.9.0a12 Cross-Tenant BOLA via Tombstones

Also known asGHSA-x26h-xmv8-gxf7

Published

Aug 19, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-76236.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs30th percentile — riskier than 30% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍stigmem-node

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`stigmem-node`	all versions	0.9.0a12`pip install --upgrade 'stigmem-node==0.9.0a12'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for stigmem-node, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update stigmem-node to 0.9.0a12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-76236 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### 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 Cro

O3 Security · Impact-Aware SCA

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