Is there a patch available for CVE-2026-42337?

Yes, a patch is available for CVE-2026-42337. Update the affected software to the latest version immediately.

MaxKB CVE-2026-42337

Q: What is the CVSS score of CVE-2026-42337?

CVE-2026-42337 has a CVSS 4.0 base score of 5.3 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-31988 MEDIUM

Missing Authorization (CWE-862)

2026-05-26 GitHub_M

Authentication Bypass Maxkb

5.3

CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.3 MEDIUM

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Patch available

May 26, 2026 - 22:02 EUVD

Analysis Generated

May 26, 2026 - 21:35 vuln.today

CVSS changed

May 26, 2026 - 21:22 NVD

5.3 (MEDIUM)

CVE Published

May 26, 2026 - 20:19 nvd

UNKNOWN (no severity yet)

DescriptionGitHub Advisory

MaxKB is an open-source AI assistant for enterprise. MaxKB 2.8.0 and prior are vulnerable to a broken access control vulnerability in the OSS file service URL fetch API (chat/api/oss/get_url). The endpoint uses application_id from the URL path without validating ownership, allowing attackers to perform operations under other applications’ policies. This vulnerability is fixed in 2.8.1.

AnalysisAI

Broken access control in MaxKB 2.8.0 and earlier exposes the OSS file service URL fetch API (chat/api/oss/get_url) to cross-application data access by authenticated low-privilege users who supply arbitrary application_id values in the URL path. Because the endpoint performs no ownership validation against the requesting session, any authenticated user can retrieve OSS file URLs scoped to applications they do not own, violating multi-tenant isolation. No public exploit code exists and the issue is not listed in CISA KEV; a vendor-released patch is available in version 2.8.1.

Technical ContextAI

MaxKB is an open-source enterprise AI knowledge-base assistant maintained by 1Panel-dev (CPE: cpe:2.3:a:1panel-dev:maxkb:*:*:*:*:*:*:*:*). The vulnerable component is the OSS (Object Storage Service) file service endpoint at chat/api/oss/get_url, which accepts an application_id path parameter to scope which application's stored files are referenced. CWE-862 (Missing Authorization) describes the root cause: the server processes the application_id and returns the associated file URL without first verifying that the authenticated caller has entitlement to that application. This is structurally an Insecure Direct Object Reference (IDOR) pattern - user-controlled input directly selects a server-side resource, and the authorization gate that should enforce ownership is absent.

RemediationAI

The primary and recommended remediation is upgrading to MaxKB 2.8.1, which is the vendor-released patch that introduces ownership validation for the application_id parameter on the chat/api/oss/get_url endpoint. Full upgrade guidance is available in the vendor advisory at https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-2jmj-gwvg-3gp2. If an immediate upgrade is not operationally feasible, restrict network-layer access to the chat/api/oss/get_url path at the reverse proxy or API gateway to only authenticated users belonging to specific, known application contexts - note this may partially disrupt legitimate chat-initiated file retrieval workflows and does not eliminate the flaw. Additionally, audit API access logs for chat/api/oss/get_url requests where the application_id in the path does not correspond to the authenticated user's registered applications, as a detection measure to identify prior or ongoing exploitation attempts.