CVE-2026-27890 HIGH

CVE-2026-27890: Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments

Vendor Firebirdsql
Product firebird
Weakness CWE-119
Published April 17, 2026
Last update April 17, 2026
View on NVD All CVEs

CVSS base score

8.2/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

What the vulnerability does

01Description

Firebird is an open-source relational database management system. In versions prior to 5.0.4, 4.0.7 and 3.0.14, when processing CNCT_specific_data segments during authentication, the server assumes segments arrive in strictly ascending order. If segments arrive out of order, the Array class's grow() method computes a negative size value, causing a SIGSEGV crash. An unauthenticated attacker who knows only the server's IP and port can exploit this to crash the server. This issue has been fixed in versions 5.0.4, 4.0.7 and 3.0.14.

Key dates

02Disclosure timeline

April 17, 2026 CVE published
April 17, 2026 Record updated