CVE-2026-6500: OpenConcerto Password Disclosure Flaw

CVE-2026-6500 Overview

CVE-2026-6500 is a plaintext password storage vulnerability in ILM Informatique OpenConcerto version 1.7.5. The flaw allows a local authenticated user to retrieve embedded sensitive credentials stored without encryption. OpenConcerto is an open-source enterprise resource planning (ERP) and accounting application used by small and mid-sized businesses.

The issue is tracked under CWE-256: Plaintext Storage of a Password. Exploitation requires local access and low privileges, with no user interaction. Successful retrieval of stored credentials can expose downstream systems and databases that OpenConcerto integrates with.

Critical Impact
A local attacker with low privileges can read plaintext passwords embedded by OpenConcerto and reuse them to access connected services or databases.

Affected Products

ILM Informatique OpenConcerto 1.7.5
Deployments using embedded credential storage in OpenConcerto configuration
Downstream services authenticated by credentials stored in the affected ERP

Discovery Timeline

2026-05-04 - CVE-2026-6500 published to NVD
2026-05-05 - Last updated in NVD database

Technical Details for CVE-2026-6500

Vulnerability Analysis

The vulnerability stems from how OpenConcerto persists authentication secrets. Passwords required for application functions, such as database or service connections, are written to disk in cleartext rather than protected with encryption or a key-derivation function. Any actor with read access to the relevant configuration or data files can retrieve these secrets directly.

The attack is local: the adversary must already have a foothold on the system hosting OpenConcerto. Privileges required are low, meaning a standard user account on the host, or a process running with that level of access, is sufficient. No user interaction is needed.

The immediate impact is confidentiality loss for the stored credentials. Because credentials are commonly reused for downstream resources such as database servers, mail relays, or API integrations, the disclosed secrets can extend an attacker's reach beyond OpenConcerto itself. The EPSS score is 0.013%, reflecting low observed exploitation activity, but credential theft remains a high-value post-compromise objective.

Root Cause

The root cause is the absence of a secure secret-storage mechanism. OpenConcerto 1.7.5 does not apply encryption, hashing, or operating-system-level protected storage to embedded passwords. The CWE-256 classification indicates the application persists the password in a recoverable cleartext form, which violates standard secret-handling guidance.

Attack Vector

An attacker with a local account, or code execution as an unprivileged user, locates the OpenConcerto configuration files or embedded data store. The attacker reads the file using normal file-system APIs and extracts the cleartext password fields. The retrieved credentials are then used to authenticate to integrated systems.

No dedicated exploit code is required. The vulnerability is described in prose only because no verified proof-of-concept is published. Refer to the OpenConcerto Version Release Notes for vendor-published details.

Detection Methods for CVE-2026-6500

Indicators of Compromise

Unexpected read access to OpenConcerto configuration files by non-application user accounts
Authentication events on integrated databases or services originating from hosts other than the OpenConcerto application server
New or unusual outbound connections from workstations using credentials embedded in OpenConcerto
File-copy or archive activity targeting OpenConcerto data directories

Detection Strategies

Monitor file-system access to OpenConcerto installation paths and flag reads by accounts other than the service principal
Correlate authentication logs from databases referenced by OpenConcerto with the source host to identify credential reuse from unexpected systems
Hunt for processes that enumerate or copy ERP configuration files, such as cat, type, copy, or scripted readers

Monitoring Recommendations

Enable file integrity monitoring on OpenConcerto configuration directories
Forward host audit logs and database authentication logs to a central analytics platform for correlation
Alert on first-time use of OpenConcerto-derived service accounts from new source addresses

How to Mitigate CVE-2026-6500

Immediate Actions Required

Restrict file-system permissions on OpenConcerto configuration and data directories to the service account only
Rotate every credential embedded in OpenConcerto 1.7.5, including database, SMTP, and API service passwords
Inventory hosts running OpenConcerto 1.7.5 and prioritize them for upgrade once a fixed version is available
Review historical access to the configuration files to identify potential prior exposure

Patch Information

No specific fixed version is identified in the published CVE record. Consult the OpenConcerto Version Release Notes for vendor updates and apply the latest release that addresses CWE-256 plaintext storage. Validate that upgraded installations no longer write cleartext passwords to configuration files.

Workarounds

Place OpenConcerto data directories on encrypted file systems to limit offline disclosure
Apply strict access control lists so only the OpenConcerto service user can read configuration files
Use database-side controls such as IP allow-listing and least-privilege accounts to reduce the value of stolen credentials
Segment the OpenConcerto host from general user workstations to limit local access

bash

# Configuration example: restrict access to OpenConcerto data directory on Linux
sudo chown -R openconcerto:openconcerto /opt/openconcerto
sudo chmod -R 700 /opt/openconcerto
sudo find /opt/openconcerto -type f -name '*.properties' -exec chmod 600 {} \;