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CVE-2026-27890

Firebirdsql Firebird buffer overflow

8.2 HIGHPublic exploitEPSS 0.72%
  1. Published17 Apr 2026

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products

Firebirdsql Firebird≥ 4.0.0 < 4.0.7 · ≥ 5.0.0 < 5.0.4 · < 3.0.14

Remediation

Fixed in
Firebirdsql Firebird≥ 4.0.7

References

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Frequently asked

Is CVE-2026-27890 being actively exploited?

CVE-2026-27890 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.72%.

How severe is CVE-2026-27890?

CVE-2026-27890 has a CVSS 3.1 base score of 8.2, rated high. EPSS estimates a 0.72% probability of exploitation.

Which products are affected by CVE-2026-27890?

Affected products include Firebirdsql Firebird.

How do I fix CVE-2026-27890?

Upgrade affected software to a fixed version, for example Firebirdsql Firebird 4.0.7 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-27890 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.