CVE-2026-33337: Firebird has a buffer overflow when parsing corrupted slice packets

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-17 · updated 2026-10-26
Weakness: CWE-120

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.

Affected products

FirebirdSQL firebird: from 3.0.0 before 3.0.14; from 4.0.0 before 4.0.7; from 5.0.0 before 5.0.4 — fixed in 3.0.14, 4.0.7, 5.0.4

How to fix

Upgrade to a fixed version: FirebirdSQL firebird 3.0.14, 4.0.7, 5.0.4. Check the vendor advisory for mitigations.

References

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