Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.
CWE-49 Variant Incomplete
Path Equivalence: 'filename/' (Trailing Slash)
This vulnerability occurs when an application accepts file or directory paths that end with a slash (e.g., 'documents/') without properly normalizing them. This can confuse the system's path…
Definition
What is CWE-49?
This vulnerability occurs when an application accepts file or directory paths that end with a slash (e.g., 'documents/') without properly normalizing them. This can confuse the system's path resolution logic, potentially allowing an attacker to bypass security checks and access files or directories they shouldn't.
At its core, this issue is about inconsistent path handling. Many file systems and APIs treat a path like 'public/data' and 'public/data/' as equivalent, pointing to the same directory. However, an application's custom security logic—like an allowlist or a path traversal check—might only validate the first version. When the system later resolves the trailing slash version to its canonical form, it could access a resource that bypassed the initial validation.
To prevent this, developers should always normalize paths before performing any security operations. This means stripping trailing slashes (or adding them consistently) and converting the path to a single, standard format. Rely on well-tested library functions for path canonicalization instead of custom string checks, and apply all authorization rules after normalization to ensure the validated path is the same one the operating system ultimately uses.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-49
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Overlaps infoleak
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Application server allows remote attackers to read source code for .jsp files by appending a / to the requested URL.
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Bypass Basic Authentication for files using trailing "/"
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Read sensitive files with trailing "/"
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Web server allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.
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Directory traversal vulnerability in server allows remote attackers to read protected files via .. (dot dot) sequences in an HTTP request.
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 pseudo
MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Sicheres Codebeispiel
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.
Präventions-Checkliste
How to prevent CWE-49
- 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.
Erkennungssignale
How to detect CWE-49
Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.
Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.
Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.
CWE-49
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-49?
Wie gravierend ist CWE-49?
Welche Sprachen oder Plattformen sind von CWE-49 betroffen?
Wie kann ich CWE-49 verhindern?
Wie erkennt und behebt Plexicus CWE-49?
Wo erfahre ich mehr über CWE-49?
Frequently asked questions
Was ist CWE-49?
This vulnerability occurs when an application accepts file or directory paths that end with a slash (e.g., 'documents/') without properly normalizing them. This can confuse the system's path resolution logic, potentially allowing an attacker to bypass security checks and access files or directories they shouldn't.
Wie gravierend ist CWE-49?
MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.
Welche Sprachen oder Plattformen sind von CWE-49 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-49 verhindern?
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.
Wie erkennt und behebt Plexicus CWE-49?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-49 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-49?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/49.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-49
CWE-41 Parent
Improper Resolution of Path Equivalence
This vulnerability occurs when an application fails to properly handle different text representations that refer to the same file or…
CWE-42 Sibling
Path Equivalence: 'filename.' (Trailing Dot)
This vulnerability occurs when a system accepts file or directory paths that end with a dot (like 'file.txt.' or 'folder.') without…
CWE-44 Sibling
Path Equivalence: 'file.name' (Internal Dot)
This vulnerability occurs when an application accepts file paths containing internal dots (like 'file.ordir') without properly checking…
CWE-46 Sibling
Path Equivalence: 'filename ' (Trailing Space)
This vulnerability occurs when an application processes file paths that end with a space character (like 'document.txt ') without properly…
CWE-47 Sibling
Path Equivalence: ' filename' (Leading Space)
This vulnerability occurs when an application accepts file or directory paths that begin with a space character (like ' filename'),…
CWE-48 Sibling
Path Equivalence: 'file name' (Internal Whitespace)
This vulnerability occurs when an application accepts file paths containing internal spaces (like 'file name') without proper validation.…
CWE-50 Sibling
Path Equivalence: '//multiple/leading/slash'
This vulnerability occurs when an application accepts file or directory paths containing multiple leading slashes (like…
CWE-51 Sibling
Path Equivalence: '/multiple//internal/slash'
This vulnerability occurs when an application accepts file or directory paths containing multiple consecutive forward slashes (e.g.,…
CWE-52 Sibling
Path Equivalence: '/multiple/trailing/slash//'
This vulnerability occurs when an application accepts file or directory paths containing multiple consecutive forward slashes (like…
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.