CWE-665 初始化不恰当

Improper Initialization

结构: Simple

Abstraction: Class

状态: Draft

被利用可能性: Medium


The software does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.


This can have security implications when the associated resource is expected to have certain properties or values, such as a variable that determines whether a user has been authenticated or not.


  • cwe_Nature: ChildOf cwe_CWE_ID: 664 cwe_View_ID: 1000 cwe_Ordinal: Primary


Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}


范围 影响 注释
Confidentiality ['Read Memory', 'Read Application Data'] When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Access Control Bypass Protection Mechanism If security-critical decisions rely on a variable having a "0" or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.
Availability DoS: Crash, Exit, or Restart The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in other environments.


DM-2 Automated Dynamic Analysis

This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Initialization problems may be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

DM-12 Manual Dynamic Analysis

Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.


MIT-3 Requirements

策略: Language Selection

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.

Architecture and Design


Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.



Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.



Pay close attention to complex conditionals that affect initialization, since some conditions might not perform the initialization.



Avoid race conditions (CWE-362) during initialization routines.

Build and Compilation


Run or compile your software with settings that generate warnings about uninitialized variables or data.



Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.


Here, a boolean initiailized field is consulted to ensure that initialization tasks are only completed once. However, the field is mistakenly set to true during static initialization, so the initialization code is never reached.

bad Java

private boolean initialized = true;
public void someMethod() {
if (!initialized) {

// perform initialization tasks

initialized = true;

The following code intends to limit certain operations to the administrator only.

bad Perl

$username = GetCurrentUser();
$state = GetStateData($username);
if (defined($state)) {
$uid = ExtractUserID($state);

# do stuff
if ($uid == 0) {

If the application is unable to extract the state information - say, due to a database timeout - then the $uid variable will not be explicitly set by the programmer. This will cause $uid to be regarded as equivalent to "0" in the conditional, allowing the original user to perform administrator actions. Even if the attacker cannot directly influence the state data, unexpected errors could cause incorrect privileges to be assigned to a user just by accident.

The following code intends to concatenate a string to a variable and print the string.

bad C

char str[20];
strcat(str, "hello world");
printf("%s", str);

This might seem innocent enough, but str was not initialized, so it contains random memory. As a result, str[0] might not contain the null terminator, so the copy might start at an offset other than 0. The consequences can vary, depending on the underlying memory.

If a null terminator is found before str[8], then some bytes of random garbage will be printed before the "hello world" string. The memory might contain sensitive information from previous uses, such as a password (which might occur as a result of CWE-14 or CWE-244). In this example, it might not be a big deal, but consider what could happen if large amounts of memory are printed out before the null terminator is found.

If a null terminator isn't found before str[8], then a buffer overflow could occur, since strcat will first look for the null terminator, then copy 12 bytes starting with that location. Alternately, a buffer over-read might occur (CWE-126) if a null terminator isn't found before the end of the memory segment is reached, leading to a segmentation fault and crash.


标识 说明 链接
CVE-2001-1471 chain: an invalid value prevents a library file from being included, skipping initialization of key variables, leading to resultant eval injection.
CVE-2008-3637 Improper error checking in protection mechanism produces an uninitialized variable, allowing security bypass and code execution.
CVE-2008-4197 Use of uninitialized memory may allow code execution.
CVE-2008-2934 Free of an uninitialized pointer leads to crash and possible code execution.
CVE-2007-3749 OS kernel does not reset a port when starting a setuid program, allowing local users to access the port and gain privileges.
CVE-2008-0063 Product does not clear memory contents when generating an error message, leading to information leak.
CVE-2008-0062 Lack of initialization triggers NULL pointer dereference or double-free.
CVE-2008-0081 Uninitialized variable leads to code execution in popular desktop application.
CVE-2008-3688 chain: Uninitialized variable leads to infinite loop.
CVE-2008-3475 chain: Improper initialization leads to memory corruption.
CVE-2008-5021 Composite: race condition allows attacker to modify an object while it is still being initialized, causing software to access uninitialized memory.
CVE-2005-1036 Permission bitmap is not properly initialized, leading to resultant privilege elevation or DoS.
CVE-2008-3597 chain: game server can access player data structures before initialization has happened leading to NULL dereference
CVE-2009-2692 chain: uninitialized function pointers can be dereferenced allowing code execution
CVE-2009-0949 chain: improper initialization of memory can lead to NULL dereference
CVE-2009-3620 chain: some unprivileged ioctls do not verify that a structure has been initialized before invocation, leading to NULL dereference


映射的分类名 ImNode ID Fit Mapped Node Name
PLOVER Incorrect initialization
CERT C Secure Coding ARR02-C Explicitly specify array bounds, even if implicitly defined by an initializer
The CERT Oracle Secure Coding Standard for Java (2011) DCL00-J Prevent class initialization cycles
Software Fault Patterns SFP4 Unchecked Status Condition


  • CAPEC-26
  • CAPEC-29