The product utilizes multiple threads, processes, components, or systems to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes.
View on MITRESynchronization refers to a variety of behaviors and mechanisms that allow two or more independently-operating processes or threads to ensure that they operate on shared resources in predictable ways that do not interfere with each other. Some shared resource operations cannot be executed atomically; that is, multiple steps must be guaranteed to execute sequentially, without any interference by other processes. Synchronization mechanisms vary widely, but they may include locking, mutexes, and semaphores. When a multi-step operation on a shared resource cannot be guaranteed to execute independent of interference, then the resulting behavior can be unpredictable. Improper synchronization could lead to data or memory corruption, denial of service, etc.
Use industry standard APIs to synchronize your code.
No detection method information available for this CWE.
The following function attempts to acquire a lock in order to perform operations on a shared resource.
However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.
void f(pthread_mutex_t *mutex) { pthread_mutex_lock(mutex); /* access shared resource */ pthread_mutex_unlock(mutex); }The following function attempts to acquire a lock in order to perform operations on a shared resource.
However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.
int f(pthread_mutex_t *mutex) { int result; result = pthread_mutex_lock(mutex);if (0 != result)return result; /* access shared resource */ return pthread_mutex_unlock(mutex); }The following code intends to fork a process, then have both the parent and child processes print a single line.
One might expect the code to print out something like:
static void print (char * string) { char * word;int counter;for (word = string; counter = *word++; ) { putc(counter, stdout);fflush(stdout); /* Make timing window a little larger... */ sleep(1); } } int main(void) { pid_t pid; pid = fork();if (pid == -1) {exit(-2);}else if (pid == 0) {print("child\n");}else {print("PARENT\n");}exit(0); }Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV.
View DetailsAttacker provides invalid address to a memory-reading function, causing a mutex to be unlocked twice
View DetailsCWE-662: Improper Synchronization is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product utilizes multiple threads, processes, components, or systems to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes. Synchronization refers to a variety of behaviors and mechanisms that allow two or more independently-operating processes or threads to ensure that they operate on shared resources in predictable ways that do not interfere with each other. Some shared resource operations cannot be executed atomically; that is, multiple steps must be guaranteed to execute sequentially, without any interference by other processes. Synchronization mechanisms vary widely, but they may include locking, mutexes, and semaphores. When a multi-step operation on a shared resource cannot be guaranteed to execute independent of interference, then the resulting behavior can be unpredictable. Improper synchronization could lead to data or memory corruption, denial of service, etc.
If exploited, CWE-662 (Improper Synchronization) it can compromise Integrity, Confidentiality and Other, leading to outcomes such as Modify Application Data, Read Application Data and Alter Execution Logic.
Recommended mitigations for CWE-662 include: Use industry standard APIs to synchronize your code.
CWE-662 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
MITRE documents real CVEs mapped to CWE-662, including CVE-2021-1782 and CVE-2009-0935. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-662 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.