CVE-2026-27890 — Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments
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…
Published: 2026-04-17 · CVSS: 8.2 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7