CVE-2024-43367

Boa is an embeddable and experimental Javascript engine written in Rust. Starting in version 0.16 and prior to version 0.19.0, a wrong assumption made when handling ECMAScript's `AsyncGenerator` operations can cause an uncaught exception on certain scripts. Boa's implementation of `AsyncGenerator` makes the assumption that the state of an `AsyncGenerator` object cannot change while resolving a promise created by methods of `AsyncGenerator` such as `%AsyncGeneratorPrototype%.next`, `%AsyncGeneratorPrototype%.return`, or `%AsyncGeneratorPrototype%.throw`. However, a carefully constructed code could trigger a state transition from a getter method for the promise's `then` property, which causes the engine to fail an assertion of this assumption, causing an uncaught exception. This could be used to create a Denial Of Service attack in applications that run arbitrary ECMAScript code provided by an external user. Version 0.19.0 is patched to correctly handle this case. Users unable to upgrade to the patched version would want to use `std::panic::catch_unwind` to ensure any exceptions caused by the engine don't impact the availability of the main application.

Boa is an embeddable and experimental Javascript engine written in Rust. Starting in version 0.16 and prior to version 0.19.0, a wrong assumption made when handling ECMAScript's `AsyncGenerator` operations can cause an uncaught exception on certain scripts. Boa's implementation of `AsyncGenerator` makes the assumption that the state of an `AsyncGenerator` object cannot change while resolving a promise created by methods of `AsyncGenerator` such as `%AsyncGeneratorPrototype%.next`, `%AsyncGeneratorPrototype%.return`, or `%AsyncGeneratorPrototype%.throw`. However, a carefully constructed code could trigger a state transition from a getter method for the promise's `then` property, which causes the engine to fail an assertion of this assumption, causing an uncaught exception. This could be used to create a Denial Of Service attack in applications that run arbitrary ECMAScript code provided by an external user. Version 0.19.0 is patched to correctly handle this case. Users unable to upgrade to the patched version would want to use `std::panic::catch_unwind` to ensure any exceptions caused by the engine don't impact the availability of the main application.

A wrong assumption made when handling ECMAScript's AsyncGenerator operations can cause an uncaught exception on certain scripts. ## Details Boa's implementation of AsyncGenerator makes the assumption that the state of an AsyncGenerator object cannot change while resolving a promise created by methods of AsyncGenerator such as %AsyncGeneratorPrototype%.next, %AsyncGeneratorPrototype%.return, or %AsyncGeneratorPrototype%.throw. However, a carefully constructed code could trigger a state transition from a getter method for the promise's then property, which causes the engine to fail an assertion of this assumption, causing an uncaught exception. This could be used to create a Denial Of Service attack in applications that run arbitrary ECMAScript code provided by an external user. ## Patches Version 0.19.0 is patched to correctly handle this case. ## Workarounds Users unable to upgrade to the patched version would want to use std::panic::catch_unwind to ensure any exceptions caused by the engine don't impact the availability of the main application.

A wrong assumption made when handling ECMAScript's `AsyncGenerator` operations can cause an uncaught exception on certain scripts. ## Details Boa's implementation of `AsyncGenerator` makes the assumption that the state of an `AsyncGenerator` object cannot change while resolving a promise created by methods of `AsyncGenerator` such as `%AsyncGeneratorPrototype%.next`, `%AsyncGeneratorPrototype%.return`, or `%AsyncGeneratorPrototype%.throw`. However, a carefully constructed code could trigger a state transition from a getter method for the promise's `then` property, which causes the engine to fail an assertion of this assumption, causing an uncaught exception. This could be used to create a Denial Of Service attack in applications that run arbitrary ECMAScript code provided by an external user. ## Patches Version 0.19.0 is patched to correctly handle this case. ## Workarounds Users unable to upgrade to the patched version would want to use [`std::panic::catch_unwind`](https://doc.rust-lang.org/std/panic/fn.catch_unwind.html) to ensure any exceptions caused by the engine don't impact the availability of the main application. ## References - https://github.com/boa-dev/boa/commit/69ea2f52ed976934bff588d6b566bae01be313f7 - https://github.com/tc39/ecma262/security/advisories/GHSA-g38c-wh3c-5h9r

Boa es un motor Javascript integrable y experimental escrito en Rust. A partir de la versión 0.16 y antes de la versión 0.19.0, una suposición incorrecta al manejar las operaciones `AsyncGenerator` de ECMAScript puede causar una excepción no detectada en ciertos scripts. La implementación de Boa de `AsyncGenerator` supone que el estado de un objeto `AsyncGenerator` no puede cambiar mientras se resuelve una promesa creada por métodos de `AsyncGenerator` como `%AsyncGeneratorPrototype%.next`, `%AsyncGeneratorPrototype%.return`, o `%AsyncGeneratorPrototype%.throw`. Sin embargo, un código cuidadosamente construido podría desencadenar una transición de estado desde un método getter para la propiedad "then" de la promesa, lo que hace que el motor falle en la afirmación de esta suposición, provocando una excepción no detectada. Esto podría usarse para crear un ataque de denegación de servicio en aplicaciones que ejecutan código ECMAScript arbitrario proporcionado por un usuario externo. La versión 0.19.0 tiene un parche para manejar correctamente este caso. Los usuarios que no puedan actualizar a la versión parcheada querrán usar `std::panic::catch_unwind` para garantizar que las excepciones causadas por el motor no afecten la disponibilidad de la aplicación principal.