CVE-2026-4251 Overview
A vulnerability has been identified in CityData CityChat up to version 0.12.6 on Android. This security flaw involves the unprotected storage of credentials within the application's file structure, specifically in resources/assets/flutter_assets/assets/credentials.json. The vulnerability allows an attacker with local access to potentially extract sensitive credential information from the application's assets.
Critical Impact
Local attackers may gain access to stored credentials, potentially exposing Google Cloud service account keys and enabling unauthorized access to Dialogflow data within the CityChat application ecosystem.
Affected Products
- CityData CityChat up to version 0.12.6 (Android)
- ai.citydata.citychat Android application package
Discovery Timeline
- 2026-03-16 - CVE-2026-4251 published to NVD
- 2026-03-17 - Last updated in NVD database
Technical Details for CVE-2026-4251
Vulnerability Analysis
This vulnerability represents an insecure data storage flaw within the CityChat Android application. The application stores sensitive credential information in a plaintext JSON file located at resources/assets/flutter_assets/assets/credentials.json. This file is accessible within the application package and can be extracted by an attacker who has local access to the device.
The vulnerability is classified under CWE-255 (Credentials Management Errors), indicating improper handling of authentication credentials. According to external analysis, the exposed credentials may include Google Cloud service account keys that could provide access to Dialogflow services used by the application.
Root Cause
The root cause of this vulnerability lies in the application's decision to bundle sensitive credential files within the Flutter assets directory. Mobile applications should never include static credentials in the application package, as Android APK files can be decompiled and inspected. The credentials.json file containing service account keys is packaged with the application assets, making it accessible to anyone who can obtain the APK file or has physical access to a device with the application installed.
Attack Vector
The attack requires local access to an Android device with CityChat installed, or access to the application's APK file. An attacker would need to:
- Obtain the CityChat APK through device extraction or third-party APK repositories
- Decompile or extract the APK contents
- Navigate to the resources/assets/flutter_assets/assets/ directory
- Access the credentials.json file containing the exposed credentials
- Utilize the extracted Google Cloud service account credentials to access backend services
The attack is considered high complexity due to the requirement of local access and the technical knowledge needed to extract and utilize the credentials effectively.
Detection Methods for CVE-2026-4251
Indicators of Compromise
- Unexpected access to Google Cloud Dialogflow APIs using the application's service account credentials
- Unusual API call patterns or geographic anomalies in Google Cloud audit logs associated with the CityChat service account
- Evidence of APK extraction or decompilation tools on organizational devices
Detection Strategies
- Monitor Google Cloud audit logs for unauthorized API access attempts using the affected service account
- Implement anomaly detection for Dialogflow service usage patterns that deviate from normal application behavior
- Scan for presence of CityChat versions 0.12.6 and earlier on managed devices using mobile device management (MDM) solutions
Monitoring Recommendations
- Enable detailed logging on Google Cloud services associated with the CityChat application
- Configure alerts for authentication events from unexpected IP addresses or locations using the service account
- Review application permissions and data access patterns on enterprise-managed Android devices
How to Mitigate CVE-2026-4251
Immediate Actions Required
- Remove or uninstall CityData CityChat version 0.12.6 and earlier from all managed devices until a patched version is available
- Rotate any Google Cloud service account credentials that may have been exposed through the application
- Review Google Cloud audit logs for any signs of unauthorized access using the potentially compromised credentials
Patch Information
The vendor was contacted early about this disclosure but did not respond. No official patch is currently available. Users should monitor for updates from CityData and upgrade to a patched version when released. For technical details about this vulnerability, see the VulDB Entry and the Notion Analysis on Google Cloud Exposure.
Workarounds
- Uninstall the CityChat application until a secure version is released
- If the application is required, limit installation to devices that do not contain other sensitive data or applications
- Implement network-level controls to restrict access to Google Cloud APIs from untrusted sources
- Consider using mobile application management (MAM) solutions to sandbox the application and limit its potential impact
Since no verified code examples are available for this vulnerability, the attack mechanism involves extracting the credentials.json file from the Flutter assets directory within the APK. Organizations should consult the external references for detailed technical analysis.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
