Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-943 Class Incomplete
Improper Neutralization of Special Elements in Data Query Logic
This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special…
Definition
What is CWE-943?
This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special elements that change the query's intended logic, potentially accessing or manipulating data in unauthorized ways.
Attackers can exploit this flaw to manipulate query logic in several harmful ways. They can alter search criteria to return different records, append extra commands, or change the number or order of results. This isn't just about stealing data; if your application logic assumes a specific result—like a single administrative user record—manipulating the query can cause it to incorrectly grant permissions or make flawed decisions based on tainted results.
While SQL injection is the most well-known example, this risk applies to many query languages. NoSQL databases, LDAP queries, XPath, and other data querying systems (like HTSQL, DQL, or XQuery) are also vulnerable if input isn't properly neutralized. The core issue is trusting user input within any command that interprets logic, not just traditional SQL.
Real-world impact
Real-world CVEs caused by CWE-943
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NoSQL injection in product for building eLearning courses allows password resets using a query processed by the Mongoose find function
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NoSQL injection in team collaboration product
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NoSQL injection in a PaaS platform using a MongoDB operator
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Injection using Documentum Query Language (DQL)
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Injection using Documentum Query Language (DQL)
How attackers exploit it
Step-by-step attacker path
- 1
The following code dynamically constructs and executes a SQL query that searches for items matching a specified name. The query restricts the items displayed to those where owner matches the user name of the currently-authenticated user.
- 2
The query that this code intends to execute follows:
- 3
However, because the query is constructed dynamically by concatenating a constant base query string and a user input string, the query only behaves correctly if itemName does not contain a single-quote character. If an attacker with the user name wiley enters the string:
- 4
for itemName, then the query becomes the following:
- 5
The addition of the:
Vulnerable code example
Vulnerable C#
The following code dynamically constructs and executes a SQL query that searches for items matching a specified name. The query restricts the items displayed to those where owner matches the user name of the currently-authenticated user.
...
string userName = ctx.getAuthenticatedUserName();
string query = "SELECT * FROM items WHERE owner = '" + userName + "' AND itemname = '" + ItemName.Text + "'";
sda = new SqlDataAdapter(query, conn);
DataTable dt = new DataTable();
sda.Fill(dt);
... Attacker payload
However, because the query is constructed dynamically by concatenating a constant base query string and a user input string, the query only behaves correctly if itemName does not contain a single-quote character. If an attacker with the user name wiley enters the string:
name' OR 'a'='a Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-943
- Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
- Implementation Validate input at trust boundaries; use allowlists, not denylists.
- Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
- Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
- Operation Monitor logs for the runtime signals listed in the next section.
Detection signals
How to detect CWE-943
Plexicus auto-detects CWE-943 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-943?
How serious is CWE-943?
What languages or platforms are affected by CWE-943?
How can I prevent CWE-943?
How does Plexicus detect and fix CWE-943?
Where can I learn more about CWE-943?
Frequently asked questions
What is CWE-943?
This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize user-controlled input. This allows an attacker to inject special elements that change the query's intended logic, potentially accessing or manipulating data in unauthorized ways.
How serious is CWE-943?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-943?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-943?
Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.
How does Plexicus detect and fix CWE-943?
Plexicus's SAST engine matches the data-flow signature for CWE-943 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-943?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/943.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-943
CWE-74 Parent
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
This vulnerability occurs when an application uses untrusted external input to build a command, query, or data structure for another…
CWE-1236 Sibling
Improper Neutralization of Formula Elements in a CSV File
This vulnerability occurs when an application writes user-supplied data into a CSV file without properly sanitizing special characters.…
CWE-75 Sibling
Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)
This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or…
CWE-77 Sibling
Improper Neutralization of Special Elements used in a Command ('Command Injection')
This vulnerability occurs when an application builds a system command using untrusted user input without properly sanitizing it. An…
CWE-78 Sibling
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
OS Command Injection occurs when an application builds a system command using untrusted, external input without properly sanitizing it.…
CWE-79 Sibling
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
This vulnerability occurs when a web application fails to properly sanitize or encode user-supplied input before displaying it on a…
CWE-88 Sibling
Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
This vulnerability occurs when an application builds a command string for execution by another component, but fails to properly separate…
CWE-89 Sibling
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
SQL Injection occurs when an application builds a database query using untrusted user input without properly sanitizing it. This allows an…
CWE-91 Sibling
XML Injection (aka Blind XPath Injection)
XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents…
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