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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 17, 2026 Sources: CVE List NVD
NVD MITRE
8.2CVSS
HIGH

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

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

Weaknesses

CWE-119CWE-787

Affected Products

firebird
FirebirdSQL

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14
github.com
https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7
github.com
https://github.com/FirebirdSQL/firebird/releases/tag/v5.0.4
github.com
and 1 more references View all →

Timeline

Published
Apr 17, 2026
Last Updated
Apr 17, 2026

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