CVE-2026-33337
Received Received - Intake
Buffer Overflow in Firebird xdr_datum() Allows Remote Crash

Publication date: 2026-04-17

Last updated on: 2026-04-27

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2026-04-17
Last Modified
2026-04-27
Generated
2026-06-16
AI Q&A
2026-04-17
EPSS Evaluated
2026-06-14
NVD
CVE-2026-33337
EUVD
EUVD-2026-23482
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
firebirdsql firebird From 4.0.0 (inc) to 4.0.7 (exc)
firebirdsql firebird From 5.0.0 (inc) to 5.0.4 (exc)
firebirdsql firebird From 3.0.0 (inc) to 3.0.14 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-120 The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
CWE-502 The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
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Executive Summary

This vulnerability exists in the Firebird open-source relational database management system in versions prior to 5.0.4, 4.0.7, and 3.0.14. It occurs when the xdr_datum() function deserializes a slice packet without properly validating that the length of a cstring fits within the slice descriptor bounds. This allows a cstring longer than the allocated buffer to overflow it.

An unauthenticated attacker can exploit this vulnerability by sending a specially crafted packet to the Firebird server, which may cause the server to crash or lead to other security impacts.

Impact Analysis

The primary impact of this vulnerability is that an attacker can cause a denial of service by crashing the Firebird server. Since the attacker does not need to be authenticated, this can be done remotely and without prior access.

While the CVSS score indicates no confidentiality or integrity impact, the availability impact is high, meaning the database service could be disrupted, potentially affecting applications and users relying on it.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade Firebird to a fixed version. The issue has been resolved in versions 5.0.4, 4.0.7, and 3.0.14. Applying these updates will prevent exploitation of the vulnerability.

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