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-366 Base Draft
Race Condition within a Thread
This vulnerability occurs when two or more threads within the same application access and manipulate a shared resource (like a variable, data structure, or file) without proper synchronization.…
Definition
What is CWE-366?
This vulnerability occurs when two or more threads within the same application access and manipulate a shared resource (like a variable, data structure, or file) without proper synchronization. Because the threads can execute in an unpredictable order, they can corrupt the resource's state, leading to crashes, incorrect calculations, or data loss.
Unlike race conditions between separate processes, this issue happens entirely within a single program's threads. It's a flaw in the program's internal logic where the developer assumed certain operations would complete in a specific sequence, but the operating system's thread scheduler can interleave them arbitrarily. Common triggers include checking a flag or counter in one thread while another is modifying it, or performing non-atomic 'read-modify-write' operations on shared data.
To prevent this, developers must use proper synchronization primitives like mutexes, semaphores, or atomic operations. These tools create critical sections that ensure only one thread can access the shared resource at a time, guaranteeing predictable and valid states. Failing to implement synchronization correctly—or incorrectly assuming certain operations are thread-safe—leaves the application's behavior undefined and unreliable.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-366
-
Chain: two threads in a web browser use the same resource (CWE-366), but one of those threads can destroy the resource before the other has completed (CWE-416).
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 example demonstrates the weakness.
int foo = 0;
int storenum(int num) {
static int counter = 0;
counter++;
if (num > foo) foo = num;
return foo;
} 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-366
- Architecture and Design Use locking functionality. This is the recommended solution. Implement some form of locking mechanism around code which alters or reads persistent data in a multithreaded environment.
- Architecture and Design Create resource-locking validation checks. If no inherent locking mechanisms exist, use flags and signals to enforce your own blocking scheme when resources are being used by other threads of execution.
Erkennungssignale
How to detect CWE-366
Plexicus erkennt CWE-366 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.
Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.
Häufig gestellte Fragen Was ist CWE-366?
Wie gravierend ist CWE-366?
Welche Sprachen oder Plattformen sind von CWE-366 betroffen?
Wie kann ich CWE-366 verhindern?
Wie erkennt und behebt Plexicus CWE-366?
Wo erfahre ich mehr über CWE-366?
Frequently asked questions
Was ist CWE-366?
This vulnerability occurs when two or more threads within the same application access and manipulate a shared resource (like a variable, data structure, or file) without proper synchronization. Because the threads can execute in an unpredictable order, they can corrupt the resource's state, leading to crashes, incorrect calculations, or data loss.
Wie gravierend ist CWE-366?
MITRE stuft die Exploit-Wahrscheinlichkeit als mittel ein — eine Ausnutzung ist realistisch, erfordert aber meist bestimmte Bedingungen.
Welche Sprachen oder Plattformen sind von CWE-366 betroffen?
MITRE lists the following affected platforms: C, C++, Java, C#.
Wie kann ich CWE-366 verhindern?
Use locking functionality. This is the recommended solution. Implement some form of locking mechanism around code which alters or reads persistent data in a multithreaded environment. Create resource-locking validation checks. If no inherent locking mechanisms exist, use flags and signals to enforce your own blocking scheme when resources are being used by other threads of execution.
Wie erkennt und behebt Plexicus CWE-366?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-366 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-366?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/366.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-366
CWE-362 Parent
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
A race condition occurs when multiple processes or threads access a shared resource simultaneously without proper coordination, creating a…
CWE-1223 Sibling
Race Condition for Write-Once Attributes
This vulnerability occurs when an untrusted software component wins a race condition and writes to a hardware register before the trusted…
CWE-1298 Sibling
Hardware Logic Contains Race Conditions
A hardware race condition occurs when security-critical logic circuits receive signals at slightly different times, creating temporary…
CWE-364 Sibling
Signal Handler Race Condition
A signal handler race condition occurs when a program's signal handling routine is vulnerable to timing issues, allowing its state to be…
CWE-367 Sibling
Time-of-check Time-of-use (TOCTOU) Race Condition
This vulnerability occurs when a program verifies a resource's state (like a file's permissions or existence) but then uses it after that…
CWE-368 Sibling
Context Switching Race Condition
This vulnerability occurs when an application switches between different security contexts (like privilege levels or domains) using a…
CWE-421 Sibling
Race Condition During Access to Alternate Channel
A race condition occurs when an application opens a secondary communication channel intended for an authorized user, but fails to secure…
CWE-689 Sibling
Permission Race Condition During Resource Copy
This vulnerability occurs when a system copies a file or resource but delays setting its final permissions until the entire copy operation…
Bereit, wenn du es bist
Schluss mit dem Bezahlen pro Entwickler.
Schließ den Kreislauf.
Plexicus ist die KI-native ASPM, die scannt, filtert, fixt, pentestet und erklärt — autonom. Unbegrenzte Entwickler, unbegrenzte Repos, Fair-Use-KI-Aktionen. Echter kostenloser Tarif, €269/mo jährlich, wenn du bereit bist.