Vulnerability Report

CVE-2026-27890

Title: Firebird Unauthenticated SIGSEGV Crash during Authentication

Memory Corruption

Proof Of Concept

No public PoC currently indexed for CVE-2026-27890.

CWE Category CWE-119

Published Date Apr 17, 2026

Modified Date Apr 24, 2026

Exploit Status Not Found

Score 8.2 CVSS v3.1

Exploit Probability (EPSS)

0.58%

Vulnerability Summary

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.

Impacted Vendors

firebirdsql 1

firebird 1

Reference Links

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

CVSS v3.1

Source Entity [email protected]

Severity HIGH

8.2

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

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

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-27890 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

April 24, 2026 MODIFIED

Vulnerability data updated via NVD.

April 24, 2026 MODIFIED

Vulnerability data updated via NVD.

April 20, 2026 MODIFIED

Vulnerability data updated via NVD.

April 17, 2026 MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


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

Affected Stack

No specific products linked.