CVE-2026-27890CWE-119CWE-787

Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments

High · published April 17, 2026

CVSS v3.1
8.2
EPSS
1%
Percentile
53.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
CVSS v4.0
Not supplied
EPSS
0.00719 · 53.3th percentile
Weaknesses
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer; CWE-787 · Out-of-bounds Write
Published
2026-04-17T18:14Z
EPSS history
Timeline
  • 17 APR 18:14Z
    Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments
    cvelistv5