Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.
CWE-825 Base Incomplete
Expired Pointer Dereference
This vulnerability occurs when a program tries to use a pointer that still points to a memory location that has already been freed or released.
Definition
What is CWE-825?
This vulnerability occurs when a program tries to use a pointer that still points to a memory location that has already been freed or released.
This issue, often called a 'use-after-free' scenario, happens when your code frees a block of memory but accidentally keeps a reference (pointer) to it. Later, when that same pointer is used to read or write data, the memory may have been reallocated for a completely different purpose within your application or system. This means you're now interacting with data you didn't intend to, leading to unpredictable behavior.
The consequences depend entirely on what now occupies that memory region. You might crash the program (denial of service), read sensitive information that belongs elsewhere (information exposure), or, in the worst case, have attacker-controlled data executed as code. This makes expired pointer dereference a critical weakness that can serve as a gateway to severe security breaches.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-825
-
access of expired memory address leads to arbitrary code execution
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stale pointer issue leads to denial of service and possibly other consequences
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Chain: a message having an unknown message type may cause a reference to uninitialized memory resulting in a null pointer dereference (CWE-476) or dangling pointer (CWE-825), possibly crashing the system or causing heap corruption.
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read of value at an offset into a structure after the offset is no longer valid
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
The following code shows a simple example of a use after free error:
- 2
When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.
- 3
The following code shows a simple example of a double free error:
- 4
Double free vulnerabilities have two common (and sometimes overlapping) causes:
- 5
- Error conditions and other exceptional circumstances - Confusion over which part of the program is responsible for freeing the memory
Verwundbares Codebeispiel
Vulnerable C
The following code shows a simple example of a use after free error:
char* ptr = (char*)malloc (SIZE);
if (err) {
abrt = 1;
free(ptr);
}
...
if (abrt) {
logError("operation aborted before commit", ptr);
} 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-825
- Architecture and Design Choose a language that provides automatic memory management.
- Implementation When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Erkennungssignale
How to detect CWE-825
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-825
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-825?
Wie gravierend ist CWE-825?
Welche Sprachen oder Plattformen sind von CWE-825 betroffen?
Wie kann ich CWE-825 verhindern?
Wie erkennt und behebt Plexicus CWE-825?
Wo erfahre ich mehr über CWE-825?
Frequently asked questions
Was ist CWE-825?
This vulnerability occurs when a program tries to use a pointer that still points to a memory location that has already been freed or released.
Wie gravierend ist CWE-825?
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-825 betroffen?
MITRE lists the following affected platforms: C, C++.
Wie kann ich CWE-825 verhindern?
Choose a language that provides automatic memory management. When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Wie erkennt und behebt Plexicus CWE-825?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-825 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-825?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/825.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-825
CWE-119 Parent
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 Sibling
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 Sibling
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 Sibling
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 Sibling
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 Sibling
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 Sibling
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 Sibling
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 Sibling
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…
Ressourcen
Further reading
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.