CVE-2026-40888: Frappe HR Information Disclosure Flaw

CVE-2026-40888 Overview

CVE-2026-40888 is a Broken Access Control vulnerability in Frappe HR, an open-source human resources management solution (HRMS). The vulnerability allows authenticated users with default roles to access unauthorized information by exploiting certain API endpoints, potentially exposing sensitive employee and organizational data.

Critical Impact

Authenticated users can bypass access controls to retrieve confidential HR data they should not have permission to view, potentially exposing sensitive employee information across the organization.

Affected Products

• Frappe HR versions prior to 15.58.1
• Frappe HR versions prior to 16.4.1

Discovery Timeline

• 2026-04-21 - CVE-2026-40888 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-40888

Vulnerability Analysis

This vulnerability is classified under CWE-284 (Improper Access Control), indicating that the application fails to properly restrict access to sensitive resources or functionality. In the context of Frappe HR, the flaw exists in certain API endpoints that do not adequately verify whether the requesting user has sufficient permissions to access the requested data.

Human Resources Management Systems handle highly sensitive data including employee personal information, salary details, performance reviews, and organizational structure. When access controls are improperly implemented, users with basic authentication credentials can potentially access data belonging to other employees or departments they should not have visibility into.

The vulnerability is exploitable over the network by any authenticated user with default role permissions. No user interaction is required beyond initial authentication, making this a straightforward attack for malicious insiders or compromised accounts.

Root Cause

The root cause of CVE-2026-40888 lies in insufficient authorization checks on specific API endpoints within Frappe HR. The application authenticates users successfully but fails to properly validate their authorization level when processing requests to certain endpoints. This allows users with minimal permissions to query and retrieve data that should be restricted to administrators or users with elevated privileges.

Attack Vector

The attack vector is network-based, requiring the attacker to be an authenticated user within the Frappe HR system. The attacker can craft API requests to vulnerable endpoints, bypassing the intended access control mechanisms to retrieve unauthorized information. Since the vulnerability requires only low privileges (default role) and no user interaction, it presents a significant risk of insider threat or post-compromise data exfiltration.

The vulnerability mechanism involves sending crafted API requests to endpoints that lack proper permission validation. Detailed technical information can be found in the GitHub Security Advisory GHSA-4375-7rxj-9hfx.

Detection Methods for CVE-2026-40888

Indicators of Compromise

• Unusual API request patterns from low-privileged user accounts accessing data outside their normal scope
• Elevated volume of API calls to HR data endpoints from a single user session
• Access log entries showing users retrieving records for employees or departments they don't manage
• Anomalous data export or query activities during off-hours

Detection Strategies

• Implement API request logging and monitor for access patterns that deviate from normal user behavior
• Configure alerts for users accessing records outside their designated department or team
• Review authentication logs for accounts exhibiting unusual data access patterns
• Deploy application-layer monitoring to detect API abuse targeting sensitive endpoints

Monitoring Recommendations

• Enable detailed audit logging for all API endpoints handling sensitive HR data
• Implement real-time alerting for bulk data access attempts by non-administrative users
• Establish baseline access patterns for users and departments to identify anomalies
• Regularly review access logs for signs of privilege abuse or unauthorized data retrieval

How to Mitigate CVE-2026-40888

Immediate Actions Required

• Upgrade Frappe HR to version 15.58.1 or 16.4.1 immediately to apply the security patch
• Review access logs to identify any potential exploitation prior to patching
• Audit user permissions to ensure principle of least privilege is enforced
• Temporarily restrict API access to sensitive endpoints if patching is delayed

Patch Information

Frappe has released patched versions that address this vulnerability. Organizations should update to the following versions:

• Version 15.x users: Upgrade to version 15.58.1 - GitHub Release v15.58.1
• Version 16.x users: Upgrade to version 16.4.1 - GitHub Release v16.4.1

For detailed information about the security fix, refer to the GitHub Security Advisory GHSA-4375-7rxj-9hfx.

Workarounds

• No official workarounds are available for this vulnerability according to the vendor advisory
• Applying the patch by upgrading to a fixed version is the only recommended remediation
• As a temporary measure, consider implementing additional network-level access controls to limit API exposure

# Upgrade Frappe HR to patched version
# For version 15.x branch:
bench update --apps hrms --upgrade

# Verify installed version after upgrade
bench version --format json | grep hrms
# Expected output should show version 15.58.1 or higher for v15 branch
# or version 16.4.1 or higher for v16 branch