CVE-2026-27890: Firebirdsql Firebird

High severity, CVSS 8.2. EPSS: 0.7% chance of exploitation in the next 30 days.

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.

Affected products

• Firebirdsql Firebird: before 3.0.14 (fixed in 3.0.14); from 4.0.0, before 4.0.7 (fixed in 4.0.7); from 5.0.0, before 5.0.4 (fixed in 5.0.4)

Published 2026-04-17. Last modified 2026-06-17.