CVE-2026-35147: HCL DFXServer Auth Bypass Vulnerability

CVE-2026-35147 Overview

CVE-2026-35147 is a broken authentication vulnerability in HCL DFXServer. The application fails to verify user authentication status when accessing specific API endpoints. Unauthenticated attackers can interact with these endpoints and perform unauthorized actions without valid credentials. The flaw is classified under [CWE-639] (Authorization Bypass Through User-Controlled Key) and exposes API functionality directly over the network. Successful exploitation impacts data confidentiality and enables limited integrity changes without requiring user interaction.

Critical Impact
Unauthenticated remote attackers can invoke sensitive HCL DFXServer API endpoints and access or modify protected resources without valid credentials.

Affected Products

HCL DFXServer (refer to vendor advisory for affected versions)
HCL Software product line components integrating DFXServer APIs
Deployments exposing DFXServer API endpoints to untrusted networks

Discovery Timeline

2026-07-16 - CVE CVE-2026-35147 published to NVD
2026-07-16 - Last updated in NVD database

Technical Details for CVE-2026-35147

Vulnerability Analysis

The vulnerability resides in the API request handling logic of HCL DFXServer. Specific endpoints do not enforce authentication checks before executing privileged operations. An attacker sends crafted HTTP requests directly to these endpoints over the network. The server processes the requests as if they originated from an authenticated session.

The attack requires no user interaction and no prior credentials. The confidentiality impact is high because attackers can read protected data through the exposed endpoints. Integrity impact is limited to modifications permitted by the exposed API surface. Availability is not directly affected by the flaw itself.

Root Cause

The root cause is missing authentication enforcement at the API layer. The application relies on client-side or session-context assumptions rather than validating each request against an authenticated principal. This aligns with [CWE-639], where authorization decisions depend on user-controlled inputs instead of verified identity. Every affected endpoint should have applied a server-side authentication gate before invoking business logic.

Attack Vector

Exploitation is performed remotely over the network. An attacker enumerates DFXServer API paths and issues direct HTTP requests to endpoints that lack authentication checks. Because the server does not challenge the request, the attacker receives responses containing sensitive data or triggers unauthorized state changes. No credentials, tokens, or session cookies are required to complete the request. See the HCL Software Knowledge Base Article for vendor-specific technical details.

// No verified proof-of-concept code is available.
// Refer to the HCL Software Knowledge Base Article for vendor details.

Detection Methods for CVE-2026-35147

Indicators of Compromise

HTTP requests to DFXServer API endpoints without valid Authorization headers or session cookies returning 2xx responses.
Access log entries showing successful API calls from unknown or external IP addresses to sensitive endpoints.
Anomalous data retrieval volumes from DFXServer processes outside normal application workflows.

Detection Strategies

Compare API access logs against expected authenticated session identifiers and flag requests missing valid tokens.
Baseline normal API endpoint usage and alert on invocation patterns originating outside authenticated user contexts.
Deploy web application firewall rules that require authentication headers on all DFXServer API paths.

Monitoring Recommendations

Enable verbose API access logging on DFXServer and forward logs to a centralized SIEM for correlation.
Monitor egress traffic from DFXServer hosts for unexpected data transfers indicating unauthorized enumeration.
Track HTTP response codes on affected endpoints and alert on unauthenticated 200 responses.

How to Mitigate CVE-2026-35147

Immediate Actions Required

Apply vendor updates referenced in the HCL Software Knowledge Base Article as soon as they are available.
Restrict network access to DFXServer API endpoints using firewall rules or reverse proxy allowlists.
Audit recent API access logs for signs of unauthenticated exploitation prior to patching.

Patch Information

HCL has published guidance in the vendor knowledge base article KB0131782. Administrators should consult the HCL Software Knowledge Base Article for fixed versions, patch identifiers, and upgrade instructions specific to their DFXServer deployment.

Workarounds

Place DFXServer behind an authenticating reverse proxy that enforces credential validation on every request.
Block external access to DFXServer API paths at the network perimeter until patches are deployed.
Disable or isolate any non-essential API endpoints exposed by DFXServer to reduce the attack surface.

bash

# Example reverse proxy configuration requiring authentication on DFXServer API paths
location /dfxserver/api/ {
    auth_request /auth-validate;
    proxy_pass http://dfxserver_backend;
    proxy_set_header X-Original-URI $request_uri;
}

location = /auth-validate {
    internal;
    proxy_pass http://auth_service/validate;
    proxy_pass_request_body off;
    proxy_set_header Content-Length "";
    proxy_set_header X-Original-URI $request_uri;
}