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

Critical 10.0 Published 17 Apr 2026 Updated 22 Apr 2026

An authenticated user with CREATE FUNCTION privileges can achieve remote code execution via path traversal in the external engine plugin loader.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-40342?

CVE-2026-40342 is a critical path traversal vulnerability in FirebirdSQL firebird, published on 17 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official 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.

Weakness: CWE-94, CWE-427, CWE-73, CWE-22

Which versions are affected by CVE-2026-40342?

It affects 1 product.

Products include Firebirdsql Firebird.

How do I fix CVE-2026-40342?

Upgrade to a fixed version.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-40342 being exploited?

There is no known exploitation of CVE-2026-40342 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-40342, ECHO-6873-b8db-a927, GHSA-7pxc-h3rv-r257, UBUNTU-CVE-2026-40342.