CVE-2026-121009 in SQL::Abstract
Summary
by MITRE • 11/04/2026
SQL::Abstract versions from 1.90_01 before 2.000001_04 for Perl skip the injection_guard check for function names given with -func.
injection_guard is documented to apply to every function name, but only the { -name => ... } shorthand goes through it. The explicit { -func => [ $name, ... ] } form puts $name into the SQL unchecked.
An application that relies on injection_guard to reject an untrusted function name passed with -func allows SQL injection.
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified in Perl's SQL::Abstract module represents a critical failure in input validation logic within versions ranging from 1.90_01 up to, but not including, version 2.000001_04. This library is widely used for generating dynamic SQL queries by abstracting the underlying database syntax differences between various relational databases such as MySQL, PostgreSQL, and Oracle. The core security mechanism intended to prevent injection attacks within this module is the injection_guard subroutine, which is designed to sanitize or reject potentially malicious input before it is incorporated into a query string. However, due to an implementation oversight in how different argument formats are processed, there exists a significant discrepancy in how function names are validated depending on the method used to invoke them.
The technical flaw stems from inconsistent handling of two distinct syntaxes for specifying SQL functions within the module's API. When developers use the shorthand hash reference format with the key -name, such as { -name => $user_input }, the input is correctly passed through the injection_guard check. This ensures that any characters or patterns deemed dangerous are either escaped or rejected before query construction proceeds. Conversely, when developers utilize the explicit array reference syntax with the key -func, specifically in the form of { -func => [ $function_name, @args ] }, the module bypasses this security checkpoint entirely. The code path for the -func argument directly interpolates the provided function name into the SQL statement without invoking any sanitization or validation routines. This inconsistency creates a blind spot where an attacker can inject arbitrary SQL commands by exploiting the unchecked execution of function names passed via the -func parameter.
From an operational perspective, this vulnerability allows for severe SQL injection attacks against applications that rely on SQL::Abstract to build queries involving dynamic functions. An attacker who controls any part of the input fed into the -func argument can execute arbitrary database operations. This could include extracting sensitive data from other tables by appending UNION SELECT statements, modifying or deleting records through INSERT, UPDATE, and DELETE commands, or even executing administrative tasks if the database user has elevated privileges. The impact is particularly dangerous because many developers assume that using the module's built-in abstraction layer provides complete protection against injection, leading to a false sense of security when utilizing the -func syntax for complex queries involving stored procedures or dynamic function calls.
This vulnerability aligns with CWE-89, commonly known as Improper Neutralization of Special Elements used in an SQL Command, specifically falling under subcategories related to unvalidated input affecting command structure. In terms of offensive cyber operations and threat modeling, this flaw facilitates the MITRE ATT&CK technique T1059, which covers Command and Scripting Interpreter activities, allowing attackers to execute commands within the database environment. It also relates to T1190, Exploiting Public-Facing Application, as it targets a common web application component used for data retrieval and manipulation. The root cause is classified under CWE-20, Improper Input Validation, where the software fails to verify that inputs meet expected criteria before processing them in security-critical contexts.
To mitigate this risk, organizations using affected versions of SQL::Abstract must immediately upgrade to version 2.000001_04 or later, where the injection_guard logic has been corrected to apply uniformly across all input methods including the -func argument. For applications that cannot be updated instantly due to dependency constraints, a temporary workaround involves avoiding the use of untrusted data in the function name position when using the -func syntax. Instead, developers should restrict function names to hardcoded, whitelisted values or implement custom validation logic before passing any dynamic input to SQL::Abstract functions. Additionally, implementing parameterized queries where possible and employing Web Application Firewalls can provide an additional layer of defense by detecting anomalous patterns in SQL traffic generated by the application. Regular security audits focusing on database interaction layers are recommended to ensure no other similar inconsistencies exist within the codebase.