CVE-2026-77517

Deferred Deferred - Pending Action

Stored XSS and Content Modification in MaxKB AI Assistant

Publication date: 2026-09-21

Last updated on: 2026-09-21

Assigner: GitHub, Inc.

Description

MaxKB is an open-source AI assistant for enterprise. From version 2.0.0 through 2.10.2-lts, document and paragraph operate routes authorize only knowledge_id in the request path, then query the target Document by document_id or Paragraph by paragraph_id without confirming that the object belongs to that knowledge base. A normal workspace user with a known victim document or paragraph UUID can use an attacker-owned knowledge-base path to read or modify content in another user's knowledge base. No fixed version is available as of this review.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-21

Last Modified

2026-09-21

Generated

2026-09-22

AI Q&A

2026-09-22

EPSS Evaluated

N/A

NVD

CVE-2026-77517

Affected Vendors & Products

Vendor	Product	Version / Range
maxkb	maxkb	From 2.0.0 (inc) to 2.10.2-lts (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-862	The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
CWE-639	The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

Executive Summary

MaxKB versions 2.0.0 through 2.10.2-lts have an authorization flaw in document and paragraph routes. These routes only verify the knowledge_id in the request path but do not confirm if the target document or paragraph belongs to that knowledge base. This allows unauthorized users with a known document or paragraph UUID to access or modify content in another user's knowledge base via an attacker-controlled path.

Detection Guidance

This vulnerability involves unauthorized access to documents or paragraphs in MaxKB due to improper authorization checks. To detect it, review MaxKB logs for unusual access patterns to document or paragraph endpoints, especially from non-admin users. Check for requests to paths like /api/v1/knowledge_bases/{knowledge_id}/documents/{document_id} or similar where the knowledge_id does not match the user's permitted knowledge base. Look for repeated or anomalous UUID references in requests.

Impact Analysis

If you use MaxKB in this version range, an attacker with a known document or paragraph ID could read or modify your sensitive knowledge base content. This could lead to data leaks, unauthorized changes, or misuse of your enterprise's information.

Compliance Impact

This vulnerability could violate compliance requirements like GDPR or HIPAA by enabling unauthorized access to protected data. Exposure of sensitive information may result in legal penalties, reputational damage, or loss of trust.

Mitigation Strategies

Upgrade to a fixed version of MaxKB if available. If no fixed version exists, restrict access to document and paragraph routes to prevent unauthorized access. Review knowledge base permissions and ensure users cannot access unrelated documents or paragraphs.

Hi! I’m here to help you understand CVE-2026-77517. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70