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-500 Variant Draft
Public Static Field Not Marked Final
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Definition
What is CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Public static fields act as global variables within your application's classloader. Because they are public, any other class can directly read and, crucially, modify their value without using proper getter or setter methods. This bypasses any validation, logging, or synchronization logic you might have in place, leading to unpredictable state changes that are difficult to trace and debug.
To prevent this, you should mark any necessary public static fields as `final` to make them constants. If a field truly needs to be mutable, consider making it private and providing controlled access through static methods, applying the principle of encapsulation even to static members to maintain data integrity and thread safety.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-500
Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.
- 2
Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.
- 3
Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.
- 4
Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.
Verwundbares Codebeispiel
Vulnerable C++
The following examples use of a public static String variable to contain the name of a property/configuration file for the application.
class SomeAppClass {
public:
static string appPropertiesConfigFile = "app/properties.config";
...
} Sicheres Codebeispiel
Secure C++
Having a public static variable that is not marked final (constant) may allow the variable to the altered in a way not intended by the application. In this example the String variable can be modified to indicate a different on nonexistent properties file which could cause the application to crash or caused unexpected behavior.
class SomeAppClass {
public:
static const string appPropertiesConfigFile = "app/properties.config";
...
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Präventions-Checkliste
How to prevent CWE-500
- Architecture and Design Clearly identify the scope for all critical data elements, including whether they should be regarded as static.
- Implementation Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
Erkennungssignale
How to detect CWE-500
CWE-500
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.
Häufig gestellte Fragen Was ist CWE-500?
Wie gravierend ist CWE-500?
Welche Sprachen oder Plattformen sind von CWE-500 betroffen?
Wie kann ich CWE-500 verhindern?
Wie erkennt und behebt Plexicus CWE-500?
Wo erfahre ich mehr über CWE-500?
Frequently asked questions
Was ist CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Wie gravierend ist CWE-500?
MITRE stuft die Exploit-Wahrscheinlichkeit als hoch ein — diese Schwachstelle wird aktiv in freier Wildbahn ausgenutzt und sollte priorisiert behoben werden.
Welche Sprachen oder Plattformen sind von CWE-500 betroffen?
MITRE lists the following affected platforms: C++, Java.
Wie kann ich CWE-500 verhindern?
Clearly identify the scope for all critical data elements, including whether they should be regarded as static. Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
Wie erkennt und behebt Plexicus CWE-500?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-500 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.
Wo erfahre ich mehr über CWE-500?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/500.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-500
Bereit, das Wesentliche zu validieren?
Bereit zu validieren, was zählt.
Plexicus ist Proof-Driven AppSec: validierte Funde, kontextuelles Verständnis und geprüfte Remediation — in Evidenz verankert, mit Ihnen gescoped.