Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
CWE-823 Base Incompleto
Use of Out-of-range Pointer Offset
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as…
Definición
What is CWE-823?
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as beyond the bounds of an array or structure.
Pointers are designed to reference memory, but software logic typically expects them to operate within specific boundaries, like an array's allocated space. When an offset—often from user input, a miscalculation, or corrupted data—pushes the pointer beyond these boundaries, it can read or write to arbitrary, unintended memory locations.
An attacker who controls this offset can exploit this to leak sensitive data, corrupt critical program variables, crash the application, or potentially execute malicious code. The core issue is a failure to properly validate that the pointer arithmetic result remains within the legitimate range of the target data structure before it is used.
Impacto en el mundo real
Real-world CVEs caused by CWE-823
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Invalid offset in undocumented opcode leads to memory corruption.
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Multimedia player uses untrusted value from a file when using file-pointer calculations.
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Spreadsheet program processes a record with an invalid size field, which is later used as an offset.
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Instant messaging library does not validate an offset value specified in a packet.
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Language interpreter does not properly handle invalid offsets in JPEG image, leading to out-of-bounds memory access and crash.
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negative offset leads to out-of-bounds read
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untrusted offset in kernel
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"blind trust" of an offset value while writing heap memory allows corruption of function pointer,leading to code execution
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
Vulnerable pseudo
MITRE no ha publicado un ejemplo de código para esta CWE. El patrón siguiente es ilustrativo — consulta Recursos para referencias canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} 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-823
- 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-823
CWE-823
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Preguntas frecuentes ¿Qué es CWE-823?
¿Qué gravedad tiene CWE-823?
¿Qué lenguajes o plataformas se ven afectados por CWE-823?
¿Cómo puedo prevenir CWE-823?
¿Cómo detecta y corrige Plexicus CWE-823?
¿Dónde puedo aprender más sobre CWE-823?
Frequently asked questions
¿Qué es CWE-823?
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as beyond the bounds of an array or structure.
¿Qué gravedad tiene CWE-823?
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-823?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-823?
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-823?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-823 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-823?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/823.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-823
CWE-119 Padre
Improper Restriction of Operations within the Bounds of a Memory Buffer
This vulnerability occurs when software accesses a memory buffer but reads from or writes to a location outside its allocated boundary.…
CWE-120 Hermano
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
This vulnerability occurs when a program copies data from one memory location to another without first verifying that the source data will…
CWE-123 Hermano
Write-what-where Condition
A write-what-where condition occurs when an attacker can control both the data written and the exact memory location where it's written,…
CWE-125 Hermano
Out-of-bounds Read
An out-of-bounds read occurs when software accesses memory outside the boundaries of a buffer, array, or similar data structure, reading…
CWE-130 Hermano
Improper Handling of Length Parameter Inconsistency
This vulnerability occurs when a program reads a structured data packet or message but fails to properly validate that the declared length…
CWE-466 Hermano
Return of Pointer Value Outside of Expected Range
This vulnerability occurs when a function returns a memory pointer that points outside the expected buffer range, potentially exposing…
CWE-786 Hermano
Access of Memory Location Before Start of Buffer
This vulnerability occurs when software attempts to read from or write to a memory location positioned before the official start of a…
CWE-787 Hermano
Out-of-bounds Write
This vulnerability occurs when software incorrectly writes data outside the boundaries of its allocated memory buffer, either beyond the…
CWE-788 Hermano
Access of Memory Location After End of Buffer
This vulnerability occurs when software attempts to read from or write to a memory buffer using an index or pointer that points past the…
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Listo para validar lo que importa.
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