CVE-2026-33337
Buffer Overflow in Firebird xdr_datum() Allows Remote Crash
Publication date: 2026-04-17
Last updated on: 2026-04-27
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| 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 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. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
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.
How can this vulnerability impact me? :
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.
What immediate steps should I take to mitigate this vulnerability?
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.