Bisheng EUVD-2026-102503

Requires a valid authenticated low-privileged user account on a network-reachable BISHENG instance (PR:L); no administrative rights, user interaction, or non-default configuration is needed. The attacker exploits the GET /api/v1/knowledge/file_bbox endpoint, which fails to enforce per-user/per-tenant ownership checks on the supplied file_id, by enumerating sequential integer file_id values. The practical limiting factor is account access - self-service registration or any shared multi-tenant deployment removes this barrier, whereas single-tenant or tightly controlled-account deployments substantially reduce real-world exposure. Impact is confined to reading other users' extracted document page text (confidentiality only); no data modification or service disruption results.

This is a genuine but bounded confidentiality risk, not a top-tier emergency. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N) describes a network-reachable, low-complexity attack that requires an authenticated low-privileged account and yields high confidentiality impact with no integrity or availability impact - fully consistent with the CWE-639 IDOR described. No EPSS score, CISA KEV listing, or formal POC/exploit-code flag was provided in the input, so there is no evidence of active exploitation or automated weaponization. However, a detailed public technical write-up (hieuPenguinnn hackmd) and VulnCheck/CVE references pinpoint the exact vulnerable endpoint (GET /api/v1/knowledge/file_bbox) and the sequential-ID enumeration method, lowering the barrier to opportunistic exploitation considerably. The signals are internally consistent - there is no CVSS-versus-description conflict - but the PR:L requirement meaningfully constrains real-world risk: an attacker must first obtain a valid account on the target instance. Net: a real priority for anyone running BISHENG multi-tenant knowledge bases with untrusted or self-service users, but the limited product footprint and required authentication keep it below the urgency of an unauthenticated RCE.

An attacker registers or obtains a low-privileged account on a shared BISHENG instance, then scripts requests to GET /api/v1/knowledge/file_bbox while incrementing the file_id parameter. Because the endpoint does not verify that the requesting user owns the referenced file, the attacker harvests extracted page text from documents belonging to other users and tenants. A public technical write-up detailing this exact enumeration exists, though no packaged exploit code was flagged in the input.