CWE-1265: Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls

Description:
The product invokes code that is believed to be reentrant, but the code performs a call that unintentionally produces a nested invocation of the non-reentrant code.

Extended Description:
In a complex product, a single function call may lead to many different possible code paths, some of which may involve deeply nested calls. It may be difficult to foresee all possible code paths that could emanate from a given function call, even if that call is assumed to be reentrant. In some systems, an external actor can manipulate inputs to the system and thereby achieve a wide range of possible control flows. This is frequently a concern in products that execute scripts from untrusted sources. Examples of such products are web browsers and PDF readers. A weakness is present when one of the possible code paths resulting from a function call alters program state that the original caller assumes to be unchanged during the call.

Affected languages: Not Language-Specific
Affected technologies: Not Technology-Specific
Parent weaknesses: CWE-662

Consequences:
  - Integrity: Unexpected State

Mitigations:
  - [Architecture and Design] When architecting a system that will execute untrusted code in response to events, consider executing the untrusted event handlers asynchronously (asynchronous message passing) as opposed to executing them synchronously at the time each event fires. The untrusted code should execute at the start of 
  - [Implementation] Make sure the code (e.g., function or class) in question is reentrant by not leveraging non-local data, not modifying its own code, and not calling other non-reentrant code.

Demonstrative examples:
The implementation of the Widget class in the following C++ code is an example of code that is not designed to be reentrant. If an invocation of a method of Widget inadvertently produces a second nested invocation of a method of Widget, then data member backgroundImage may unexpectedly change during execution of the outer call.
Looking closer at this example, Widget::click() calls backgroundImage->click(), which in turn calls scriptEngine->fireOnImageClick(). The code within fireOnImageClick() invokes the appropriate script handler routine as defined by the document being rendered. In this scenario this script routine is supplied by an adversary and this malicious script makes a call to Widget::changeBackgroundImage(), deleting the Image object pointed to by backgroundImage. When control r

This is another example of C++ code that is not designed to be reentrant.
The expected order of operations is a call to Request::setup(), followed by a call to Request::send(). Request::send() calls scriptEngine->coerceToString(_data) to coerce a script-provided parameter into a string. This operation may produce script execution. For example, if the script language is ECMAScript, arbitrary script execution may result if _data is an adversary-supplied ECMAScript object having a custom toString method. If the adversary's script makes a new call to Request::setup, then when control returns to Request::send, the field uri and the local variable credentials will no longer be consistent with one another. As a result, credentials for one resource will be shared improperly with a different resour

Real-world examples:
  - CVE-2014-1772: In this vulnerability, by registering a malicious onerror handler, an adversary can produce unexpected re-entrance of a CDOMRange object. [REF-1098]
  - CVE-2018-8174: This CVE covers several vulnerable scenarios enabled by abuse of the Class_Terminate feature in Microsoft VBScript. In one scenario, Class_Terminate is used to produce an undesirable re-entrance of Sc