CVE-2025-54989 Overview
CVE-2025-54989 is a NULL pointer dereference vulnerability in Firebird, a popular open-source relational database management system. The vulnerability exists within the parsing of XDR (External Data Representation) messages received from clients. When exploited, this flaw causes the Firebird server to crash, resulting in a denial-of-service (DoS) condition that can disrupt database availability for all connected applications and services.
Critical Impact
Remote attackers can crash Firebird database servers without authentication by sending specially crafted XDR messages, causing service disruption for all dependent applications.
Affected Products
- Firebird versions prior to 3.0.13
- Firebird versions prior to 4.0.6
- Firebird versions prior to 5.0.3
Discovery Timeline
- 2025-08-15 - CVE-2025-54989 published to NVD
- 2025-11-03 - Last updated in NVD database
Technical Details for CVE-2025-54989
Vulnerability Analysis
This vulnerability is classified as CWE-476 (NULL Pointer Dereference). The flaw resides in the XDR message parsing component of Firebird's remote protocol handling. When processing client messages, the server fails to properly validate the procedure pointer before attempting to dereference it. Under certain conditions, this pointer can be NULL, causing the application to crash when it attempts to access memory at address zero.
The vulnerability is network-accessible and requires no authentication or user interaction to exploit, making it particularly dangerous for internet-facing database deployments. An attacker can trigger the crash remotely by sending malformed XDR messages to the Firebird server port.
Root Cause
The root cause lies in the src/remote/protocol.cpp file where the code attempts to access procedure->rpr_out_msg and procedure->rpr_out_format without first verifying that the procedure pointer obtained from port->port_rpr is valid. While the codebase assumed this scenario would never occur, edge cases in client message handling could result in a NULL procedure pointer being dereferenced.
Attack Vector
The attack vector is network-based and requires no privileges or user interaction. An attacker can exploit this vulnerability by:
- Establishing a connection to the Firebird database server
- Sending a specially crafted XDR message that triggers the vulnerable code path
- Causing the server to dereference a NULL procedure pointer
- Resulting in immediate server crash and denial of service
The security patch adds explicit NULL pointer validation before the dereference occurs:
rem_port* port = xdrs->x_public;
Rpr* procedure = port->port_rpr;
+ // normally that never happens
+ fb_assert(procedure);
+ if (!procedure)
+ return false;
if (msg_type == 1)
return xdr_message(xdrs, procedure->rpr_out_msg, procedure->rpr_out_format);
Source: GitHub Commit 169da595f8693fc1a65a79c741724b1bc8db9f25
Detection Methods for CVE-2025-54989
Indicators of Compromise
- Unexpected Firebird server crashes or service restarts
- Segmentation fault errors in Firebird logs referencing protocol.cpp or XDR message handling
- Connection patterns showing rapid connection attempts followed by server crashes
- Core dump files indicating NULL pointer dereference in remote protocol handling
Detection Strategies
- Monitor Firebird process stability and unexpected terminations using process monitoring tools
- Implement network intrusion detection rules to identify malformed XDR protocol messages
- Configure crash dump analysis to capture and analyze segmentation faults in Firebird processes
- Review Firebird server logs for connection anomalies or protocol parsing errors
Monitoring Recommendations
- Enable detailed logging for Firebird's network protocol handling to capture pre-crash context
- Set up automated alerts for Firebird service failures or repeated restarts
- Monitor network traffic to Firebird ports (default 3050) for unusual patterns or malformed packets
- Implement application-level health checks to detect service unavailability
How to Mitigate CVE-2025-54989
Immediate Actions Required
- Upgrade Firebird to version 3.0.13, 4.0.6, or 5.0.3 or later immediately
- Review firewall rules to restrict access to Firebird ports from untrusted networks
- Implement network segmentation to limit exposure of database servers
- Enable service monitoring to detect and automatically restart crashed Firebird instances
Patch Information
FirebirdSQL has released patched versions that address this vulnerability. The fix adds explicit NULL pointer validation before accessing the procedure pointer. Organizations should upgrade to the following patched versions:
- Firebird 3.x: Upgrade to version 3.0.13 or later
- Firebird 4.x: Upgrade to version 4.0.6 or later
- Firebird 5.x: Upgrade to version 5.0.3 or later
The security patch is available via the official Firebird commit. Additional details are available in the GitHub Security Advisory GHSA-7qp6-hqxj-pjjp. Debian users should also review the Debian LTS Announcement.
Workarounds
- Restrict network access to Firebird ports using firewall rules to allow only trusted IP addresses
- Place Firebird servers behind a reverse proxy or VPN to limit direct exposure
- Implement connection rate limiting to slow down potential exploitation attempts
- Configure automatic service restart policies to minimize downtime in case of crashes
# Configuration example - Restrict Firebird access using iptables
# Allow only trusted network to access Firebird default port
iptables -A INPUT -p tcp --dport 3050 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 3050 -j DROP
# Configure systemd to automatically restart Firebird on failure
# Add to /etc/systemd/system/firebird.service.d/override.conf
# [Service]
# Restart=always
# RestartSec=5
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
