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-91 Base Rascunho
XML Injection (aka Blind XPath Injection)
XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents or queries. This allows attackers to inject malicious XML…
Definição
What is CWE-91?
XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents or queries. This allows attackers to inject malicious XML elements or syntax, potentially altering the document's structure, extracting sensitive data, or disrupting processing logic.
XML documents use special characters like <, >, &, and " to define elements and attributes. If user input containing these characters is inserted without neutralization, an attacker can break out of intended data fields and inject new XML tags, modify queries (like XPath), or even reference external entities. This can lead to data theft, logic bypasses, or denial of service.
Preventing XML injection requires strict input validation, context-aware output encoding, and the use of parameterized XPath interfaces. Managing this at scale across numerous codebases and APIs is difficult; an ASPM platform like Plexicus can help you track and remediate these flaws across your entire stack by correlating SAST findings with runtime behavior and prioritizing the most critical exposures.
Impacto no mundo real
Real-world CVEs caused by CWE-91
Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
Identificar um caminho de código que trata input não confiável sem validação.
- 2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
- 3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
- 4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.
Exemplo de código vulnerável
Vulnerable pseudo
A MITRE não publicou um exemplo de código para este CWE. O padrão abaixo é ilustrativo — consulte os Recursos para referências canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Exemplo 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 verificação de prevenção
How to prevent CWE-91
- Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Sinais de deteção
How to detect CWE-91
O Plexicus deteta automaticamente o CWE-91 e abre um PR de correção em menos de 60 segundos.
O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.
Perguntas frequentes O que é o CWE-91?
Qual a gravidade do CWE-91?
Que linguagens ou plataformas são afetadas pelo CWE-91?
Como posso prevenir o CWE-91?
Como é que o Plexicus deteta e corrige o CWE-91?
Onde posso saber mais sobre o CWE-91?
Frequently asked questions
O que é o CWE-91?
XML Injection occurs when an application fails to properly validate or escape user-controlled input before including it in XML documents or queries. This allows attackers to inject malicious XML elements or syntax, potentially altering the document's structure, extracting sensitive data, or disrupting processing logic.
Qual a gravidade do CWE-91?
A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.
Que linguagens ou plataformas são afetadas pelo CWE-91?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-91?
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and…
Como é que o Plexicus deteta e corrige o CWE-91?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-91 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-91?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/91.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-91
CWE-74 Pai
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
This vulnerability occurs when an application uses untrusted external input to build a command, query, or data structure for another…
CWE-1236 Irmão
Improper Neutralization of Formula Elements in a CSV File
This vulnerability occurs when an application writes user-supplied data into a CSV file without properly sanitizing special characters.…
CWE-75 Irmão
Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)
This vulnerability occurs when an application fails to properly filter or encode user-supplied data containing special characters or…
CWE-77 Irmão
Improper Neutralization of Special Elements used in a Command ('Command Injection')
This vulnerability occurs when an application builds a system command using untrusted user input without properly sanitizing it. An…
CWE-78 Irmão
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
OS Command Injection occurs when an application builds a system command using untrusted, external input without properly sanitizing it.…
CWE-79 Irmão
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
This vulnerability occurs when a web application fails to properly sanitize or encode user-supplied input before displaying it on a…
CWE-88 Irmão
Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
This vulnerability occurs when an application builds a command string for execution by another component, but fails to properly separate…
CWE-89 Irmão
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
SQL Injection occurs when an application builds a database query using untrusted user input without properly sanitizing it. This allows an…
CWE-917 Irmão
Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
Expression Language Injection occurs when an application uses untrusted, external input to build an expression language statement—common…
Pronto quando você estiver
Pare de pagar por desenvolvedor.
Comece a fechar o ciclo.
O Plexicus é o ASPM nativo de IA que verifica, filtra, corrige, pentesta e explica — de forma autónoma. Programadores ilimitados, repos ilimitados, ações de IA de utilização justa. Nível gratuito real, €269/mo anual quando estiver pronto.