Description
The product uses a non-blocking model that relies on a single threaded process for features such as scalability, but it contains code that can block when it is invoked.
When an attacker can directly invoke the blocking code, or the blocking code can be affected by environmental conditions that can be influenced by an attacker, then this can lead to a denial of service by causing unexpected hang or freeze of the code. Examples of blocking code might be an expensive computation or calling blocking library calls, such as those that perform exclusive file operations or require a successful network operation. Due to limitations in multi-thread models, single-threaded models are used to overcome the resource constraints that are caused by using many threads. In such a model, all code should generally be non-blocking. If blocking code is called, then the event loop will effectively be stopped, which can be undesirable or dangerous. Such models are used in Python asyncio, Vert.x, and Node.js, or other custom event loop code.
Potential Impact
Availability
DoS: Resource Consumption (CPU)
Mitigations & Prevention
Generally speaking, blocking calls should be replaced with non-blocking alternatives that can be used asynchronously. Expensive computations should be passed off to worker threads, although the correct approach depends on the framework being used.
For expensive computations, consider breaking them up into multiple smaller computations. Refer to the documentation of the framework being used for guidance.
Related Weaknesses
Frequently Asked Questions
What is CWE-1322?
CWE-1322 (Use of Blocking Code in Single-threaded, Non-blocking Context) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Base-level weakness. The product uses a non-blocking model that relies on a single threaded process for features such as scalability, but it contains code that can block when it is invoked.
How can CWE-1322 be exploited?
Attackers can exploit CWE-1322 (Use of Blocking Code in Single-threaded, Non-blocking Context) to dos: resource consumption (cpu). This weakness is typically introduced during the Implementation phase of software development.
How do I prevent CWE-1322?
Key mitigations include: Generally speaking, blocking calls should be replaced with non-blocking alternatives that can be used asynchronously. Expensive computations should be passed off to worker threads, although
What is the severity of CWE-1322?
CWE-1322 is classified as a Base-level weakness (Medium abstraction). Its actual severity depends on the specific context and how the weakness manifests in your application.