CVE-2026-40342: Firebird: Path Traversal + Arbitrary File Write Leads to Remote Code Execution

Severity: critical (CVSS 9.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-17 · updated 2026-10-26
Weakness: CWE-22

Description

Firebird is an open-source relational database management system. In versions prior to 5.0.4, 4.0.7 and 3.0.14, the external engine plugin loader concatenates a user-supplied engine name into a filesystem path without filtering path separators or .. components. An authenticated user with CREATE FUNCTION privileges can use a crafted ENGINE name to load an arbitrary shared library from anywhere on the filesystem via path traversal. The library's initialization code executes immediately during loading, before Firebird validates the module, achieving code execution as the server's OS account. This issue has been fixed in versions 5.0.4, 4.0.7 and 3.0.14.

Affected products

FirebirdSQL firebird: 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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