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CVE-2026-27890

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

Published: Apr 17, 2026Updated: Apr 24, 2026 Sources: CVE List NVD BDUCWE-119
NVD MITRE
8.2CVSSHIGH
EPSS Score
0.5%
Top 63.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:LA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:HAvailability
High
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Weaknesses

CWE-119CWE-787

Affected Products

firebirdFirebirdSQL
On-prem
Databases / relational
firebirdfirebirdsql
On-prem
Databases / relational
РЕД ОСООО «Ред Софт»
On-premOS
Operating Systems / linux-distro
Ред База ДанныхООО «Ред Софт»
On-premDatabase
Databases / relational
FirebirdFirebird Foundation Inc.
On-prem
Databases / relational
firebirdsqloss-projectDatabasesaka firebird
ооо «ред софт»commercialRUOperating Systemsaka red soft
firebird foundation inc.oss-projectDatabasesaka firebird

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49
github.com
https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14
github.com
https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7
github.com
and 3 more references View all →

Timeline

Published
Apr 17, 2026
Last Updated
Apr 24, 2026

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