CVE-2026-27890

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.

CVSS 3.1

8.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS

0.5% chance of exploitation in the next 30 days; higher than 39% of CVEs (scores of 2026-10-26)

CWEs

CWE-119, CWE-787

Published

2026-04-17

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• firebirdsql:firebird

References

• https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14
• https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7
• https://github.com/FirebirdSQL/firebird/releases/tag/v5.0.4
• https://github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49

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