CVE-2026-82441
CVE-2026-82441 is a Improper Input Validation vulnerability. O3 Security confirms whether CVE-2026-82441 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Description A submitted topology carries two lists of blobstore keys, `dependency_jars` and `dependency_artifacts`, which the client fills in after uploading the corresponding blobs.…
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-82441.
Description
Description
A submitted topology carries two lists of blobstore keys, dependency_jars and dependency_artifacts,
which the client fills in after uploading the corresponding blobs. Nimbus performed no validation of their
contents on the submission path, yet acts on them in two places.
During cleanup of a finished topology, Nimbus deletes the keys named in those lists, and the deletion is
performed as the Nimbus subject, for which the blobstore short-circuits its ACL check. A submitter who
listed a key belonging to another topology, such as its -stormjar.jar, could therefore cause
that blob to be deleted when their own topology was cleaned up.
Separately, on acquiring leadership a Nimbus compares the dependency keys of all active topologies against the blobstore contents and surrenders leadership if any is missing. A single key that does not exist, on a single active topology, therefore causes every Nimbus to acquire leadership, surrender it and requeue indefinitely, leaving the cluster without a leader and unable to schedule, clean up or accept submissions.
Mitigation
Upgrade to 3.1.0, where a submission is refused unless every entry in both lists is a dependency blob key and exists in the blobstore.
Note that this validates new submissions only; a topology stored by an affected version with an invalid list is unaffected by the upgrade. An operator whose cluster is failing to retain a leader should inspect the Nimbus log for the dependency keys reported as missing and remove or resubmit the topology naming them.
Users who cannot upgrade immediately should restrict topology submission to trusted principals.
Credit
This issue was discovered by rzo1 while investigating an unrelated blobstore defect.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-82441 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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.
How O3 protects you
O3 pinpoints whether CVE-2026-82441 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-82441. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-82441 in your dependencies?
O3 detects CVE-2026-82441 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.