CVE-2025-65104 Overview
CVE-2025-65104 is an information disclosure vulnerability affecting the Firebird open-source relational database management system. The vulnerability exists in the FB3 client library, which incorrectly handles data length values in XSQLDA (Extended SQL Descriptor Area) fields when communicating with FB4 or higher database servers. This miscommunication results in an information leak that could expose sensitive data to unauthorized parties.
Critical Impact
Information leakage through incorrect data length handling in client-server communication could expose sensitive database content or metadata to attackers with local access.
Affected Products
- Firebird FB3 Client Library (all versions prior to FB4)
- Systems using FB3 client libraries to connect to FB4 or higher servers
Discovery Timeline
- 2026-04-17 - CVE CVE-2025-65104 published to NVD
- 2026-04-17 - Last updated in NVD database
Technical Details for CVE-2025-65104
Vulnerability Analysis
This vulnerability is classified as CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The flaw originates from a protocol compatibility issue between the FB3 client library and newer FB4+ server implementations.
When an FB3 client establishes a connection with an FB4 or higher server, the client library incorrectly calculates and transmits data length values within the XSQLDA structure. The XSQLDA is a critical data structure used in Firebird's API for describing SQL statement parameters and result columns. Due to the incorrect length calculations, memory beyond the intended buffer boundaries may be included in the communication, leading to information leakage.
The vulnerability requires local access to exploit, meaning an attacker would need to be positioned on the local system or network segment where the Firebird client-server communication occurs. While no public exploit is currently available, the nature of the vulnerability could allow interception of sensitive database content, query structures, or connection metadata.
Root Cause
The root cause lies in the FB3 client library's handling of XSQLDA field population during communication handshakes with newer server versions. The client library was not properly updated to account for changes in the wire protocol or data structure handling introduced in FB4. This results in incorrect sqllen and related length fields being populated, causing the server to interpret or expose data beyond intended boundaries.
Attack Vector
The attack vector is local, requiring the attacker to have access to the system running the Firebird client or the ability to intercept local communications between the client and server. An attacker positioned to observe or manipulate client-server traffic could:
- Monitor connections from FB3 clients to FB4+ servers
- Capture XSQLDA communication packets containing improperly sized data
- Extract leaked information from the oversized data transmissions
The vulnerability does not require high privileges to exploit, though the impact is primarily limited to confidentiality concerns with potential for integrity impact in certain scenarios.
Detection Methods for CVE-2025-65104
Indicators of Compromise
- Unexpected data lengths in Firebird client-server communication logs
- Anomalous memory access patterns in FB3 client library processes
- Unusual network traffic sizes between Firebird clients and servers
- Error messages related to XSQLDA field length mismatches
Detection Strategies
- Monitor Firebird client library versions across your environment and flag any FB3 clients connecting to FB4+ servers
- Implement network traffic analysis to detect abnormal packet sizes in Firebird wire protocol communications
- Review application logs for XSQLDA-related warnings or errors that may indicate exploitation attempts
- Deploy endpoint detection to identify FB3 client library usage patterns
Monitoring Recommendations
- Establish baseline metrics for Firebird client-server communication packet sizes
- Configure alerts for FB3 client connections to production FB4+ server instances
- Enable verbose logging on Firebird servers to capture detailed connection information
- Regularly audit client library versions deployed in production environments
How to Mitigate CVE-2025-65104
Immediate Actions Required
- Inventory all systems using Firebird FB3 client libraries
- Prioritize upgrading FB3 clients connecting to FB4 or higher servers
- Consider network segmentation to isolate legacy FB3 clients until upgrade is complete
- Review access controls for systems running Firebird clients to minimize exposure
Patch Information
The recommended remediation is to upgrade all Firebird FB3 client libraries to FB4 or higher. The fix is included in Firebird v4.0.0 and all subsequent versions. Organizations should:
- Download the latest Firebird client library from the official Firebird releases
- Test client library compatibility with existing applications in a staging environment
- Deploy the updated client libraries to production systems
- Verify successful remediation by confirming FB4+ client version in connection logs
For detailed information about this vulnerability, refer to the GitHub Security Advisory GHSA-mfpr-9886-xjhg.
Workarounds
- Restrict network access between FB3 clients and FB4+ servers using firewall rules until clients can be upgraded
- Implement encrypted connections (SSL/TLS) between Firebird clients and servers to reduce interception risk
- Temporarily downgrade server instances to FB3 if client upgrades cannot be performed immediately (not recommended for production)
- Deploy network monitoring to detect and alert on potential exploitation attempts
# Verify Firebird client library version
isql -z
# Check for FB3 client connections in server logs
grep -i "client version" /var/log/firebird/firebird.log
# Update Firebird client package (Debian/Ubuntu)
apt-get update && apt-get install firebird4.0-client
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
