CVE-2026-21836: HCL DominoIQ Auth Bypass Vulnerability

CVE-2026-21836 Overview

CVE-2026-21836 is a Broken Access Control vulnerability [CWE-862] affecting the HCL DominoIQ Retrieval-Augmented Generation (RAG) feature. Under certain circumstances, document-level access restrictions are ignored when the system determines which data to return from an AI query. An authenticated attacker can leverage this flaw to view sensitive data that should otherwise be restricted by document-level access controls.

The vulnerability impacts confidentiality but does not affect integrity or availability. Exploitation requires network access and low-level privileges, with no user interaction needed.

Critical Impact
Authenticated users can retrieve sensitive documents through AI queries that bypass document-level access restrictions in HCL DominoIQ RAG.

Affected Products

HCL DominoIQ RAG feature
Refer to the HCL Software Knowledge Base Article for specific affected versions
HCL Domino deployments leveraging DominoIQ AI capabilities

Discovery Timeline

2026-05-20 - CVE CVE-2026-21836 published to NVD
2026-05-20 - Last updated in NVD database

Technical Details for CVE-2026-21836

Vulnerability Analysis

The vulnerability resides in the DominoIQ RAG feature, which augments AI query responses by retrieving relevant documents from a Domino data store. RAG systems typically index documents and return the most relevant content snippets to the language model for response generation.

In HCL DominoIQ, the retrieval layer fails to consistently enforce Domino's document-level access control lists (ACLs) when selecting source documents for an AI query. As a result, content from documents the requesting user is not authorized to read can be surfaced in AI-generated responses.

The impact is restricted to confidentiality. An attacker cannot modify data or impair service availability through this flaw. However, sensitive documents indexed for RAG, including internal communications, HR records, or business-confidential material, may be exposed.

Root Cause

The root cause is a missing authorization check [CWE-862] in the RAG retrieval pipeline. Document-level access restrictions configured in Domino are not consulted during the AI query data selection step. The retrieval logic returns content based on relevance scoring without verifying that the requesting authenticated user has read access to the source document.

Attack Vector

Exploitation requires an authenticated user account on the target Domino environment. The attacker submits crafted natural-language queries to the DominoIQ AI interface, designed to coax the RAG layer into surfacing restricted content. Because the access check is missing rather than weak, no privilege escalation or credential theft is required. The vulnerability manifests over the network through the standard DominoIQ query interface. Refer to the HCL Software Knowledge Base Article for vendor-confirmed technical details.

Detection Methods for CVE-2026-21836

Indicators of Compromise

Unusual volume of DominoIQ AI queries from a single authenticated user account
AI query patterns referencing keywords, project names, or document identifiers the user has no business need to access
Audit log entries showing RAG retrieval of documents inconsistent with the user's role or department

Detection Strategies

Correlate DominoIQ query logs with Domino ACL membership to identify responses that include content from documents the querying user cannot directly open
Baseline normal AI query topics per user or role and alert on significant deviations
Review RAG indexing scope to identify which sensitive document libraries are exposed to AI queries

Monitoring Recommendations

Enable verbose logging for DominoIQ RAG retrievals, capturing source document references for each AI response
Forward Domino and DominoIQ logs to a centralized SIEM for retention and cross-source correlation
Monitor for spikes in AI query activity, especially from accounts with low historical usage

How to Mitigate CVE-2026-21836

Immediate Actions Required

Apply the vendor remediation documented in the HCL Software Knowledge Base Article
Audit which document libraries and databases are indexed by DominoIQ RAG and remove highly sensitive content from the AI index until patched
Review DominoIQ usage logs since the feature was enabled to identify potential prior exposure

Patch Information

HCL has published remediation guidance in the HCL Software Knowledge Base Article. Administrators should consult the advisory for fixed versions and upgrade procedures specific to their DominoIQ deployment.

Workarounds

Restrict DominoIQ RAG indexing scope to document collections that are intended to be broadly readable
Limit DominoIQ access to a smaller group of trusted users until the patch is applied
Temporarily disable the DominoIQ RAG feature in environments where sensitive documents are indexed and patching is not yet feasible