Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.
CWE-820 Base Incompleto
Missing Synchronization
This vulnerability occurs when multiple parts of your application (like threads or processes) use the same resource—such as a variable, file, or data structure—without proper coordination to control…
Definición
What is CWE-820?
This vulnerability occurs when multiple parts of your application (like threads or processes) use the same resource—such as a variable, file, or data structure—without proper coordination to control who accesses it and when.
When different parts of your code run concurrently and touch a shared resource without synchronization, the resource's state can become unpredictable. One thread might read a value while another is halfway through modifying it, or two processes might overwrite each other's changes, leading to corrupted data, crashes, or incorrect calculations that break your application's logic.
This lack of coordination creates a race condition window that attackers can potentially exploit. By carefully timing their interactions, an attacker might manipulate the shared resource into an unexpected state that bypasses security checks, leaks sensitive information, or causes the system to behave in unintended and insecure ways.
Impacto en el mundo real
Real-world CVEs caused by CWE-820
Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
The following code intends to fork a process, then have both the parent and child processes print a single line.
- 2
One might expect the code to print out something like:
- 3
``` PARENT child ```
- 4
However, because the parent and child are executing concurrently, and stdout is flushed each time a character is printed, the output might be mixed together, such as:
- 5
``` PcAhRiElNdT [blank line] [blank line] ```
Ejemplo de código vulnerable
Vulnerable C
The following code intends to fork a process, then have both the parent and child processes print a single line.
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);
} Ejemplo de código seguro
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Lista de prevención
How to prevent CWE-820
- 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.
Señales de detección
How to detect CWE-820
Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.
Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.
Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.
Plexicus detecta automáticamente CWE-820 y abre un PR de corrección en menos de 60 segundos.
Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.
Preguntas frecuentes ¿Qué es CWE-820?
¿Qué gravedad tiene CWE-820?
¿Qué lenguajes o plataformas se ven afectados por CWE-820?
¿Cómo puedo prevenir CWE-820?
¿Cómo detecta y corrige Plexicus CWE-820?
¿Dónde puedo aprender más sobre CWE-820?
Frequently asked questions
¿Qué es CWE-820?
This vulnerability occurs when multiple parts of your application (like threads or processes) use the same resource—such as a variable, file, or data structure—without proper coordination to control who accesses it and when.
¿Qué gravedad tiene CWE-820?
MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.
¿Qué lenguajes o plataformas se ven afectados por CWE-820?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-820?
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.
¿Cómo detecta y corrige Plexicus CWE-820?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-820 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-820?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/820.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-820
CWE-662 Padre
Improper Synchronization
This vulnerability occurs when a multi-threaded or multi-process application allows shared resources to be accessed by multiple threads or…
CWE-1058 Hermano
Invokable Control Element in Multi-Thread Context with non-Final Static Storable or Member Element
This happens when a method or function, designed to run in a multi-threaded environment, accesses or modifies a non-final static variable…
CWE-1096 Hermano
Singleton Class Instance Creation without Proper Locking or Synchronization
This flaw occurs when a Singleton class is implemented without proper thread-safe controls, allowing multiple instances to be created in…
CWE-366 Hermano
Race Condition within a Thread
This vulnerability occurs when two or more threads within the same application access and manipulate a shared resource (like a variable,…
CWE-543 Hermano
Use of Singleton Pattern Without Synchronization in a Multithreaded Context
This vulnerability occurs when a singleton pattern is implemented in a multithreaded application without proper synchronization,…
CWE-567 Hermano
Unsynchronized Access to Shared Data in a Multithreaded Context
This vulnerability occurs when multiple threads in an application can read and modify shared data, like static variables, without proper…
CWE-663 Hermano
Use of a Non-reentrant Function in a Concurrent Context
This vulnerability occurs when a program uses a function that is not safe for reentrancy within a concurrent environment, such as…
CWE-667 Hermano
Improper Locking
This vulnerability occurs when a program fails to correctly acquire or release a lock on a shared resource, such as a file, database…
CWE-764 Hermano
Multiple Locks of a Critical Resource
This vulnerability occurs when a critical resource, such as a file, data structure, or connection, is locked more times than the software…
Listo cuando tú lo estés
Deja de pagar por desarrollador.
Empieza a cerrar el bucle.
Plexicus es el ASPM nativo de IA que escanea, filtra, corrige, pentestea y explica — de forma autónoma. Desarrolladores ilimitados, repos ilimitados, acciones de IA de uso justo. Nivel gratuito real, €269/mo anual cuando estés listo.