Vulnerability CVE-2026-27890: Information

Description

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.

Severity: HIGH (8.2)

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

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-27890

Published: April 17, 2026

Modified: April 24, 2026

Error type identifier: CWE-119, CWE-787

Fixed packages

Package name	Branch	Fixed in version	Version from repository	Errata ID	Task #	State
firebird	sisyphus	5.0.4-alt1	5.0.4-alt1	ALT-PU-2026-7100-2	417095	Fixed
firebird	sisyphus_loongarch64	5.0.4-alt1	5.0.4-alt1	ALT-PU-2026-7495-1	-	Fixed
firebird	p11	5.0.4-alt1	5.0.4-alt1	ALT-PU-2026-7136-2	417164	Fixed

References to Advisories, Solutions, and Tools

Hyperlink	Resource
https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14	Release Notes
https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7	Release Notes
https://github.com/FirebirdSQL/firebird/releases/tag/v5.0.4	Release Notes
https://github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49	Exploit Vendor Advisory
BDU:2026-05719

Affected configurations:
1. cpe:2.3:a:firebirdsql:firebird:*:*:*:*:*:*:*:*
  End excluding
  3.0.14
  cpe:2.3:a:firebirdsql:firebird:*:*:*:*:*:*:*:*
  Start including
  4.0.0
  End excluding
  4.0.7
  cpe:2.3:a:firebirdsql:firebird:*:*:*:*:*:*:*:*
  Start including
  5.0.0
  End excluding
  5.0.4

Version: v26.2.2