CVE-2024-43367

Name of the Vulnerable Software and Affected Versions Boa versions 0.16 through 0.19.0

Description A wrong assumption in Boa's implementation of AsyncGenerator can cause an uncaught exception on certain scripts. This occurs because the state of an AsyncGenerator object is assumed not to change while resolving a promise created by methods such as %AsyncGeneratorPrototype%.next, %AsyncGeneratorPrototype%.return, or %AsyncGeneratorPrototype%.throw. However, a carefully constructed code can trigger a state transition from a getter method for the promise's then property, causing the engine to fail an assertion of this assumption and resulting in 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.

Recommendations For versions 0.16 through 0.19.0, upgrade to version 0.19.0 to correctly handle this case. For users unable to upgrade to the patched version, use std::panic::catch unwind to ensure any exceptions caused by the engine do not impact the availability of the main application.