High 8.2Published Apr 17, 2026

CVE-2026-27890Firebird has Pre-Auth DOS when Processing Out of Order CNCT_specific_data Segments

Updated under an hour ago (Oct 28, 2026, 9:00 PM ET)

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It affects FirebirdSQL firebird. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for FirebirdSQL firebird

Exploited in the last 30 days

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: 8.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness (CWE): CWE-119, CWE-787
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Apr 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

FirebirdSQL firebird firebirdsql:firebird (from the name)	from 3.0.0, < 3.0.14; from 4.0.0, < 4.0.7; from 5.0.0, < 5.0.4	CNA record
firebirdsql firebird firebirdsql:firebird	before 3.0.14; from 4.0.0 before 4.0.7; from 5.0.0 before 5.0.4	NVD

References

References

https://github.com/FirebirdSQL/firebird/security/advisories/GHSA-6crx-4g37-7j49	x-refsource-confirm, exploit, vendor-advisory
https://github.com/FirebirdSQL/firebird/releases/tag/v3.0.14	x-refsource-misc, release-notes
https://github.com/FirebirdSQL/firebird/releases/tag/v4.0.7	x-refsource-misc, release-notes
https://github.com/FirebirdSQL/firebird/releases/tag/v5.0.4	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.