MISP EUVD-2026-91717

Requires an authenticated MISP account that already holds at least read visibility of an event owned by a different organization, and the attacker must query via the deleted-attributes search or the paginated attribute listing using the deleted filter - the normal event detail view is NOT affected because it correctly restricts soft-deleted attributes to the owning org and sync-permission users. Limiting factors: exploitation is impossible for unauthenticated actors (PR:L), is only meaningful on multi-organization or federated/community instances where cross-org event visibility exists, and only soft-deleted (retracted) attributes are exposed - live/active attributes and non-visible events are not disclosed. Only confidentiality is affected; no data can be modified.

This is a genuine but low-to-moderate priority information-disclosure issue, not a critical emergency. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N) yields a 5.3 Medium score, and the impact is confined to confidentiality only (VC:L, with VI:N/VA:N) - no integrity or availability effect and no scope/subsequent-system change. The PR:L metric confirms exploitation requires an authenticated account, which substantially narrows the attacker population to existing MISP users (or federated/community partners) who already have read visibility of the target event. No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no evidence of active exploitation or weaponization - signals are consistent rather than conflicting. The realistic concern is an insider or a semi-trusted community/partner member on a shared MISP instance pulling soft-deleted intelligence from other organizations, rather than mass internet-wide exploitation. Net: schedule patching as routine hardening (especially for multi-org/community-federated deployments), but it does not warrant emergency out-of-band response.

An authenticated MISP user who belongs to Organization B but has read visibility of an event owned by Organization A issues a deleted-attributes search (or loads the paginated attribute view with the deleted filter). The vulnerable fetchAttributes/fetchPaginatedAttributes code paths return Organization A's soft-deleted attributes - IOCs and context the owner intended to retract - to the unauthorized user. No public exploit code is identified at time of analysis, but the flaw is trivially triggered through the normal search/API interface.