CWE-767

Access to Critical Private Variable via Public Method. [Permission-Issues, Improper-Control-Of-A-Resource-Through-Its-Lifetime]

Required inputs: IR

The product defines a public method that reads or modifies a private variable. If an attacker modifies the variable to contain unexpected values, this could violate assumptions from other parts of the code. Additionally, if an attacker can read the private variable, it may expose sensitive information or make it easier to launch further attacks.

Demonstrative Examples

Example 1

The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

Example Language:C++
    private: float price;
    public: void changePrice(float newPrice) {
        price = newPrice;
    }

Example 2

The following example could be used to implement a user forum where a single user (UID) can switch between multiple profiles (PID).

Example Language:Java (Unsupported language for documentation only)
    public class Client {
        private int UID;
        public int PID;
        private String userName;
        public Client(String userName){
            PID = getDefaultProfileID();
            UID = mapUserNametoUID( userName );
            this.userName = userName;
        }
        public void setPID(int ID) {
            UID = ID;
        }
    }

The programmer implemented setPID with the intention of modifying the PID variable, but due to a typo. accidentally specified the critical variable UID instead. If the program allows profile IDs to be between 1 and 10, but a UID of 1 means the user is treated as an admin, then a user could gain administrative privileges as a result of this typo.

Excerpts from CWE [https://cwe.mitre.org], Copyright (C) 2006-2026, the MITRE Corporation. See section 9.4. "3rd-Party Licenses" in the documentation for full details.

Possible Messages

Key	Text	Severity	Disabled
critical_field_write	Critical private field must not be written to in a public method.	None	False

Options

• This rule shares the following common options: exclude_in_macros, exclude_messages_in_system_headers, excludes, extend_exclude_to_macro_invocations, includes, justification_checker, languages, post_processing, provider, report_at, severity

• The following places define options that affect this rule: Stylechecks, Analysis-GlobalOptions

critical_field_patterns

critical_field_patterns : set[bauhaus.analysis.config.SearchPattern] = {'pass_?[word|key]', 'user_?name'}

List of regex patterns used to find critical fields.