CWE-908 对未经初始化资源的使用

Use of Uninitialized Resource

结构: Simple

Abstraction: Base

状态: Incomplete

被利用可能性: Medium


The software uses a resource that has not been properly initialized.


This can have security implications when the associated resource is expected to have certain properties or values.


  • 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.
Availability DoS: Crash, Exit, or Restart The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.




Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.



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



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

Build and Compilation


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


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-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-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-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
CERT C Secure Coding EXP33-C CWE More Abstract Do not read uninitialized memory