Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as low-privilege tenant
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DeliveryList other tenants' objects via GET /file/storage
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ExploitRequest presigned URL or /file/download/{object_name}
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ExecutionBypass skipped tenant check in check_file_access
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ImpactExfiltrate cross-tenant knowledge-base documents
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Object-level authorization, IDOR prevention
|
| Exploitation Conditions | Requires a multi-tenant Nexent deployment (through 2.7.0) and a valid authenticated account on that instance (PR:L) - the flaw does not grant initial access, it escalates a legitimate tenant to read other tenants' data. The specific trigger is reading objects under the knowledge_base/ path, for which check_file_access skips the tenant-ownership comparison; abuse is via GET /file/storage (to list objects / obtain presigned URLs) or GET /file/download/{object_name}. Limiting factors: single-tenant or non-shared deployments are not meaningfully exposed, exploitation is confined to knowledge-base file reads (confidentiality only - no write or deletion), and the attacker must already possess tenant credentials. No user interaction is required. |
| Impact | This is a cross-tenant authorization flaw (CWE-639) in Nexent's check_file_access, where tenant comparison is skipped for knowledge_base/ reads, letting any authenticated tenant read other tenants' knowledge-base source documents. The provided CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N/VC:H, VI:N/VA:N) correctly frames this as a network-reachable, low-complexity, low-privilege confidentiality-only issue - no integrity or availability impact - yielding 7.1. The key limiting signal is PR:L: exploitation requires a valid authenticated account on a multi-tenant deployment, so this is not a remote-unauthenticated break. No EPSS score, no CISA KEV listing, and no POC flag were provided in the input, so there is no evidence of active or at-scale exploitation; however, a detailed public technical writeup (hackmd) and a VulnCheck advisory describe the mechanism precisely, which materially lowers the effort to reproduce. Net: a genuine, credible data-confidentiality priority for anyone running Nexent as a shared multi-tenant service, but real-world risk is bounded by the niche deployment footprint and the authenticated-tenant precondition rather than being a mass-exploitable internet threat. |
| Exploit ScenarioDerived | An attacker signs up for or already holds a low-privilege account in a shared multi-tenant Nexent instance (≤2.7.0). They call GET /file/storage to enumerate knowledge-base objects belonging to other tenants and obtain presigned URLs, or directly call GET /file/download/{object_name} to retrieve another tenant's source documents. A public technical writeup describing the exact endpoints and the skipped tenant check exists, so reproduction is low-effort even though no packaged exploit was indicated in the input. |
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Alert meAnalysisAIv1 – Oct 14, 2026
Cross-tenant knowledge-base file read in Nexent through 2.7.0 allows any authenticated tenant to access other tenants' source documents by exploiting a missing tenant check in the check_file_access function for knowledge_base/ paths. Attackers in multi-tenant deployments can list objects via GET /file/storage to obtain presigned URLs or directly download files via GET /file/download/{object_name}. This is an authenticated information disclosure flaw requiring a valid account; no public exploit code or active exploitation has been identified at time of analysis.
RemediationAI
No vendor-released patch has been identified in the available data; monitor the Nexent GitHub repository for updates and upgrade to a version after 2.7.0 once available. As compensating controls, enforce tenant isolation at an API gateway or reverse proxy by validating that requested object names belong to the authenticated tenant's namespace, or restrict access to the /file/storage and /file/download endpoints for untrusted tenants. Disabling these endpoints entirely would break legitimate file access features. Additionally, review access logs for anomalous cross-tenant reads and consider limiting multi-tenant deployments to fully trusted tenants until a fix is applied. Trade-offs: gateway-level checks require custom logic and may not cover all access paths; disabling endpoints impacts functionality. Refer to the VulnCheck advisory (https://www.vulncheck.com/advisories/nexent-through-2.7.0-cross-tenant-knowledge-base-file-read-via-check-file-access) and the public write-up (https://hackmd.io/@hieuPenguinnn/nexent-knowledge-base-cross-tenant-file-read) for further details.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
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Technical ContextAI · show details
The vulnerability is a broken access control (CWE-639: Authorization Bypass Through User-Controlled Key) in Nexent's file management service, specifically the check_file_access function in backend/services/file_management_service.py. The function is intended to compare the tenant identifier of the requesting user with that of the requested object, but it skips this comparison for objects whose paths begin with knowledge_base/. This allows an authenticated user from one tenant to read files belonging to another tenant. The flaw is reachable through the /file/storage endpoint, which lists objects and returns presigned URLs, and the /file/download/{object_name} endpoint, which directly serves file content. The underlying technology involves a multi-tenant knowledge-base application where access control relies on path-based checks; the missing check enables horizontal privilege escalation (cross-tenant data access) without requiring write or delete permissions.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Network-reachable API abusable by any authenticated tenant (PR:L) with no interaction; impact is cross-tenant document disclosure only, so C:H with I:N/A:N and unchanged scope.
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
DescriptionCVE.org
Nexent through 2.7.0 contains a missing authorization vulnerability in check_file_access that allows authenticated users to read other tenants' knowledge-base files by skipping tenant comparison for knowledge_base/ reads. Attackers in multi-tenant deployments can list objects via GET /file/storage for presigned URLs or use GET /file/download/{object_name} to download other tenants' source documents.
Executive ViewAI
Nexent versions through 2.7.0 contain a cross-tenant file read vulnerability that allows users with valid accounts to access other tenants' knowledge-base source documents in multi-tenant deployments. No public exploit identified at time of analysis, but this flaw undermines tenant isolation and could expose confidential business information, intellectual property, or customer data, potentially leading to regulatory penalties and reputational damage. Leadership should prioritize assessing exposure and implementing interim controls while awaiting a vendor patch.
Restrict network access to Nexent APIs, enforce tenant isolation at the API gateway by validating object ownership, monitor for anomalous cross-tenant file access, and apply virtual patching via WAF to block unauthorized requests to /file/storage and /file/download endpoints.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
EUVD-2026-101575
GHSA-7qhg-85q3-m2xj
NVD
CVE.org
EPSS
Vulnrichment
Exploit-DB