CVE-2026-33337: firebirdsql firebird Classic Buffer Overflow

Vulnerability summary

CVE-2026-33337 is a high (CVSS 7.5) Classic Buffer Overflow vulnerability in firebirdsql firebird. EPSS estimates a 0.81% chance of exploitation in the next 30 days, higher than 56.4% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 17-04-2026
   PublishedVulnerability first disclosed.
2. 17-04-2026
   Last modifiedVulnerability information updated.

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.

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')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-502Deserialization of Untrusted DataThe product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.