CVE-2026-103237: MISP: Nested Model Alias Key Bypasses Sanitization to Modify Cross-Tenant Rows

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?

0.2%

EPSS score, percentile 13.8 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

8.3 High

CVSS v4.0 base score, given by the CNA

What should I do?

The fix introduces a defensive save() override in the base model class that refuses to persist any record where the data array simultaneously contains a nested key … Full textSolution from the CVE record.

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

Advisories and patches (1)

Which versions are affected?

Affected

• before 2.5.48

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

Solution (from the CVE record)

The fix introduces a defensive save() override in the base model class that refuses to persist any record where the data array simultaneously contains a nested key matching the model alias and other top-level scalar fields, logging a warning and returning false. Additionally, all code paths that sanitize and save records (free-text import, module result processing, object delta merge, attribute bulk edit, sighting capture, shadow attribute proposal, event report creation) now explicitly unset the nested alias key from the data array before calling save(), ensuring the ORM cannot be redirected to an attacker-chosen row. Controller-level request reshaping was also corrected to avoid creating self-referencing data structures.

Advisories and patches

• Security patch (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.

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

About this vulnerability

MISP contains an improper input validation vulnerability in its ORM save path. When a user submits data through various endpoints (attribute add/edit, event edit, free-text import, sighting capture, shadow attribute proposal, event report creation, object reference add, user admin edit), the application sanitizes the flat record by stripping the primary key and pinning the event_id or object_id t…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-103237 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 30 Sep 2026.
• The CVE record carries a CVSS v4.0 base score of 8.3 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.2% (percentile 13.8), 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 partial.
• 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: Nested Model Alias Key Bypasses Sanitization to Modify Cross-Tenant Rows

MISP contains an improper input validation vulnerability in its ORM save path. When a user submits data through various endpoints (attribute add/edit, event edit, free-text import, sighting capture, shadow attribute proposal, event report creation, object reference add, user admin edit), the application sanitizes the flat record by stripping the primary key and pinning the event_id or object_id to the caller's context. However, the underlying ORM's set() method gives priority to a nested key whose name matches the model alias and discards the outer scalar fields. An authenticated user with basic write permissions can exploit this by embedding a nested block under the model alias key inside their request. The sanitization logic (id removal, event_id pinning) is applied to the outer record, but the ORM binds to the inner record instead, which carries an attacker-chosen id and event_id. This allows the attacker to overwrite, re-parent, or soft-delete rows belonging to other organizations or events they have no read access to. Impact: - Cross-tenant data integrity compromise (attribute values rewritten, objects re-parented to attacker events, rows soft-deleted) - Affects multiple entity types: Attribute, Object, EventReport, Sighting, AttributeTag, ShadowAttribute - Requires only a low-privilege authenticated account with perm_add Affected versions: <2.5.48

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

Timeline