Missing Authorization in PostgreSQL Type Conversion

Executive Summary

This vulnerability is a missing authorization check in PostgreSQL's type conversion process. It allows a database user to run a cast function without having the required EXECUTE privilege. The issue can be triggered through foreign keys, to_json(), and other functions. An attacker must find restricted cast functions and assess their confidentiality impact, though such functions are rare.

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Detection Guidance

Detecting this vulnerability requires checking PostgreSQL versions and reviewing cast function privileges. Use 'SELECT version();' to check your PostgreSQL version. If it is below 18.7, 17.12, 16.16, 15.20, or 14.25, the system is vulnerable. To identify cast functions without EXECUTE privileges, query 'SELECT n.nspname, p.proname FROM pg_proc p JOIN pg_namespace n ON p.pronamespace = n.oid WHERE p.proacl IS NULL OR NOT EXISTS (SELECT 1 FROM pg_has_role(p.proowner, p.proacl, 'USAGE'));'

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Impact Analysis

The impact is limited due to the rarity of access-restricted cast functions. If exploited, it could allow unauthorized access to sensitive data by invoking functions without proper permissions. The low CVSS score (3.1) suggests minimal practical risk in most environments.

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Mitigation Strategies

Upgrade PostgreSQL to a patched version (18.7 or later, 17.12 or later, 16.16 or later, 15.20 or later, 14.25 or later). If upgrading is not immediately possible, restrict database user privileges to prevent unauthorized access to cast functions. Regularly audit function privileges and apply security patches promptly.

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