CVE-2026-56422: MISP Core: Mass Assignment and Object Re-ownership via Unvalidated Request Fields

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.6%

EPSS score, percentile 48.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

9.4 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (12)

Which versions are affected?

Affected

• 2.5.41 and earlier

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Advisories and patches

• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)
• github.com (Patch)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Versions not listed are: unaffected.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

Multiple MISP core controllers and model capture paths accepted client-controlled request fields such as primary keys (id) and ownership/scope foreign keys (event_id, org_id, user_id, sharing_group_id, galaxy_cluster_uuid, organisation_uuid, and related nested object identifiers) without consistently stripping, pinning, or revalidating them against the server-authorized object. In affected paths…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-56422 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 22 Jun 2026.
• The CVE record carries a CVSS v4.0 base score of 9.4 (Critical), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.6% (percentile 48.7), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact total.
• The credits in the CVE record name Anthropic (Claude) as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

MISP Core: Mass Assignment and Object Re-ownership via Unvalidated Request Fields

Multiple MISP core controllers and model capture paths accepted client-controlled request fields such as primary keys (id) and ownership/scope foreign keys (event_id, org_id, user_id, sharing_group_id, galaxy_cluster_uuid, organisation_uuid, and related nested object identifiers) without consistently stripping, pinning, or revalidating them against the server-authorized object. In affected paths, an authenticated user with access to one authorized object could submit crafted REST or form payloads that caused MISP to save data against a different object than the one checked by the authorization logic. Depending on the endpoint, this could allow object overwrite, object re-parenting, ownership transfer, unauthorized sharing-group scoping, event/object injection, proposal retargeting, or stored attacker-controlled content appearing in another user’s context. The fixes harden affected create/edit/import flows by stripping client-supplied primary keys on create-only saves, re-pinning route- or database-authorized identifiers before save operations, validating effective sharing-group scope, and adding field whitelists where ownership fields must never be editable. The initial broad fix also added a central CRUDComponent::edit() primary-key re-pin so payload-supplied IDs cannot redirect saves away from the already-authorized row. GitHub’s patch for 7acf8220c describes this central issue as CRUDComponent::edit() copying supplied fields, including a payload primary key, onto the loaded record, allowing CakePHP save() to update an arbitrary row unless the loaded ID is re-pinned.

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline