Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-799 Class Incomplete
Improper Control of Interaction Frequency
This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.
Definition
What is CWE-799?
This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.
Without proper frequency limits, both human users and automated bots can perform actions far more often than intended. This flaw is commonly exploited to launch denial-of-service (DoS) attacks, bypass business logic (like voting systems or promotional offers), or brute-force credentials by making unlimited password attempts.
Developers must implement controls like rate limiting, request throttling, and CAPTCHAs to enforce interaction boundaries. These measures are essential for protecting system availability, ensuring fair use, and preventing automated tools from exploiting core application functions.
Real-world impact
Real-world CVEs caused by CWE-799
-
Mail server allows attackers to prevent other users from accessing mail by sending large number of rapid requests.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 4
Iterate until the response leaks data, executes attacker code, or escalates privileges.
Vulnerable code example
Vulnerable C
In the following code a username and password is read from a socket and an attempt is made to authenticate the username and password. The code will continuously checked the socket for a username and password until it has been authenticated.
char username[USERNAME_SIZE];
char password[PASSWORD_SIZE];
while (isValidUser == 0) {
if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {
if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {
isValidUser = AuthenticateUser(username, password);
}
}
}
return(SUCCESS); Secure code example
Secure C
This code does not place any restriction on the number of authentication attempts made. There should be a limit on the number of authentication attempts made to prevent brute force attacks as in the following example code.
int count = 0;
while ((isValidUser == 0) && (count < MAX_ATTEMPTS)) {
if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {
if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {
isValidUser = AuthenticateUser(username, password);
}
}
count++;
}
if (isValidUser) {
return(SUCCESS);
}
else {
return(FAIL);
} 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-799
- 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-799
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
Plexicus auto-detects CWE-799 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-799?
How serious is CWE-799?
What languages or platforms are affected by CWE-799?
How can I prevent CWE-799?
How does Plexicus detect and fix CWE-799?
Where can I learn more about CWE-799?
Frequently asked questions
What is CWE-799?
This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.
How serious is CWE-799?
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-799?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-799?
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-799?
Plexicus's SAST engine matches the data-flow signature for CWE-799 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-799?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/799.html. You can also reference OWASP and NIST documentation for adjacent guidance.
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