Out-of-bounds write in Firebird - #VU126555
Published: April 20, 2026
Vulnerability identifier: #VU126555
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: N/A
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: firebird.sourceforge.net
Affected software:
Firebird
Firebird
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an out-of-bounds write in CNCT_specific_data handling when processing out-of-order CNCT_specific_data sequence segments during authentication. A remote attacker can send specially crafted sequence segments to cause a denial of service.
The issue can be triggered before authentication and may cause a SIGSEGV in the server process.
Remediation
Install security update from vendor's website.