CVE-2026-28214 Overview
CVE-2026-28214 is an Integer Overflow vulnerability affecting Firebird, an open-source relational database management system. The vulnerability exists in the ClumpletReader::getClumpletSize() function, where parsing a Wide type clumplet can cause an overflow of the totalLength value, resulting in an infinite loop. An authenticated attacker with INSERT privileges on any table can exploit this flaw by sending a crafted Batch Parameter Block, causing a denial of service condition against the database server.
Critical Impact
Authenticated users with minimal privileges can crash Firebird database servers, disrupting availability for all connected applications and services.
Affected Products
- Firebird versions prior to 5.0.4
- Firebird versions prior to 4.0.7
- Firebird versions prior to 3.0.14
Discovery Timeline
- April 17, 2026 - CVE-2026-28214 published to NVD
- April 20, 2026 - Last updated in NVD database
Technical Details for CVE-2026-28214
Vulnerability Analysis
The vulnerability resides within Firebird's clumplet parsing mechanism, specifically in the ClumpletReader::getClumpletSize() function. Clumplets are structured data elements used internally by Firebird for various parameter blocks, including Batch Parameter Blocks used during batch INSERT operations.
When processing a Wide type clumplet, the function performs arithmetic operations on the totalLength value without adequate bounds checking. This oversight allows an attacker to craft malicious input that causes the totalLength variable to overflow, wrapping around to a small or zero value. The corrupted length value then causes the parsing loop to iterate indefinitely, consuming server resources and effectively halting all database operations.
The attack requires only INSERT privileges on any table, which is commonly granted to application users, making the attack surface relatively broad in typical deployment scenarios.
Root Cause
The root cause is CWE-190: Integer Overflow or Wraparound. The ClumpletReader::getClumpletSize() function fails to validate that arithmetic operations on the totalLength variable will not exceed the maximum value for its data type. When a specially crafted Wide type clumplet is processed, the multiplication or addition operations overflow, producing an incorrect small value that causes infinite iteration in the parsing loop.
Attack Vector
The attack is network-accessible and requires authentication with INSERT privileges. An attacker constructs a malicious Batch Parameter Block containing a specially crafted Wide type clumplet designed to trigger the integer overflow. When the Firebird server processes this malformed batch request, the ClumpletReader::getClumpletSize() function enters an infinite loop, consuming CPU resources and preventing the server from handling legitimate requests.
The vulnerability can be exploited through any database connection interface that supports batch operations, including native Firebird wire protocol connections and ODBC/JDBC drivers. The attack does not require any user interaction and can be automated for sustained denial of service.
Detection Methods for CVE-2026-28214
Indicators of Compromise
- Firebird server processes consuming 100% CPU with no corresponding query activity
- Database server becoming unresponsive to connection attempts
- Abnormal Batch Parameter Block requests in database connection logs
- Service monitoring alerts indicating Firebird process hangs or timeouts
Detection Strategies
- Monitor Firebird server CPU utilization for sustained high usage patterns without corresponding legitimate query workload
- Implement query logging and review batch INSERT operations for anomalous or malformed parameter structures
- Deploy network intrusion detection rules to identify malformed Firebird wire protocol messages
- Configure alerting on database connection timeouts and service availability degradation
Monitoring Recommendations
- Enable detailed logging for batch operations and monitor for repeated failures or unusual sizes
- Implement service health checks that verify database responsiveness at regular intervals
- Monitor network traffic patterns for unusual Firebird protocol activity from authenticated sessions
- Set up automated alerting when database connection pools experience abnormal exhaustion
How to Mitigate CVE-2026-28214
Immediate Actions Required
- Upgrade Firebird to patched versions: 5.0.4, 4.0.7, or 3.0.14 depending on your major version branch
- Review and restrict INSERT privileges to only those users and applications that require them
- Implement network segmentation to limit direct database access to trusted application servers
- Monitor database servers for signs of exploitation while patches are being deployed
Patch Information
Firebird has released security patches addressing this vulnerability across all supported version branches. Users should upgrade to the following fixed versions:
- Firebird v5.0.4 for version 5.x users
- Firebird v4.0.7 for version 4.x users
- Firebird v3.0.14 for version 3.x users
For complete vulnerability details, refer to the GitHub Security Advisory GHSA-7cq5-994r-jhrf.
Workarounds
- Restrict network access to Firebird servers using firewall rules to limit connections to authorized application servers only
- Implement connection rate limiting to reduce the impact of potential exploitation attempts
- Review database user privileges and apply principle of least privilege, removing INSERT rights where not strictly necessary
- Deploy a database proxy or application firewall capable of inspecting and filtering malformed database protocol messages
# Example: Restrict Firebird network access with iptables
# Allow connections only from trusted application servers
iptables -A INPUT -p tcp --dport 3050 -s 10.0.1.100 -j ACCEPT
iptables -A INPUT -p tcp --dport 3050 -s 10.0.1.101 -j ACCEPT
iptables -A INPUT -p tcp --dport 3050 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
