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CVE-2026-33337

Firebirdsql Firebird insecure deserialization

7.5 HIGHPublic exploitEPSS 0.81%
  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 deserializing a slice packet, the xdr_datum() function does not validate that a cstring length conforms to the slice descriptor bounds, allowing a cstring longer than the allocated buffer to overflow it. An unauthenticated attacker can exploit this by sending a crafted packet to the server, potentially causing a crash or other security impact. 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
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Firebirdsql Firebird≥ 3.0.0 < 3.0.14 · ≥ 4.0.0 < 4.0.7 · ≥ 5.0.0 < 5.0.4

Remediation

Fixed in
Firebirdsql Firebird≥ 3.0.14

References

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Frequently asked

Is CVE-2026-33337 being actively exploited?

CVE-2026-33337 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.81%.

How severe is CVE-2026-33337?

CVE-2026-33337 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.81% probability of exploitation.

Which products are affected by CVE-2026-33337?

Affected products include Firebirdsql Firebird.

How do I fix CVE-2026-33337?

Upgrade affected software to a fixed version, for example Firebirdsql Firebird 3.0.14 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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