CVE-2026-40342
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedFirebird 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencePath traversal in Firebird's external engine plugin loader allows authenticated users with CREATE FUNCTION privileges to load arbitrary shared libraries by crafting ENGINE names with .. sequences, achieving immediate code execution as the server's OS account.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 3.0.14>= 4.0.0, < 4.0.7>= 5.0.0, < 5.0.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Firebird server versionQuery the server for its version using isql or a management tool: SELECT rdb$get_context('SYSTEM', 'ENGINE_VERSION') FROM rdb$database; or check the installed package/database files.Affected if The version falls within < 3.0.14, >= 4.0.0 and < 4.0.7, or >= 5.0.0 and < 5.0.4
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Verify if users or roles have CREATE FUNCTION privilegeQuery the security database for granted privileges: SELECT GRANTEE, GRANTOR, PRIVILEGE, OBJECT_NAME FROM RDB$USER_PRIVILEGES WHERE PRIVILEGE = 'C' AND OBJECT_NAME = 'FUNC$'; or inspect role definitions that include CREATE FUNCTION permissions.Affected if Any user or role beyond the DBA account holds CREATE FUNCTION privilege
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Inspect existing external function definitions for suspicious ENGINE namesQuery RDB$FUNCTIONS and RDB$FUNCTION_ARGUMENTS for external functions: SELECT f.rdb$function_name, a.rdb$engine_name FROM rdb$functions f JOIN rdb$function_arguments a ON f.rdb$function_id = a.rdb$function_id WHERE f.rdb$function_type = 1; Look for ENGINE names containing '..' or absolute/unusual paths.Affected if Any external function has an ENGINE name containing path traversal sequences ('..') or pointing outside the Firebird UDF directory
You are affected if your Firebird version is vulnerable AND at least one user has CREATE FUNCTION privilege AND a suspicious external function with a traversal ENGINE name exists.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.0.144.0.75.0.4
Upgrade to Firebird 5.0.4, 4.0.7, or 3.0.14 to obtain the patch. Until then, restrict CREATE FUNCTION privileges to trusted users only and monitor for suspicious ENGINE names containing path traversal patterns.
Upgrade to Firebird 5.0.4, 4.0.7, or 3.0.14 (matching your current major version branch)
- 1. Identify current Firebird version by running 'fbversion' or checking installation directory
- 2. Review release notes for versions 3.0.14, 4.0.7, and 5.0.4 to determine the appropriate upgrade path for your current major version
- 3. Create complete backup of all Firebird databases using gbak utility
- 4. Stop the Firebird server service or daemon
- 5. Download the appropriate fixed version installer from firebirdsql.org or your distribution's package repository
- 6. Install the upgraded Firebird version (5.0.4, 4.0.7, or 3.0.14 depending on your major version line)
- 7. Verify the plugin loader now properly sanitizes ENGINE names by checking the source code or release notes
- 8. Restart the Firebird server service
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40342 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40342 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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