CVE-2024-43367 Boa has an uncaught exception when transitioning the state of `AsyncGenerator` objects
An attacker can cause a denial of service in applications using the Boa JavaScript engine by triggering an uncaught exception via crafted async generator scripts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-43367?
CVE-2024-43367 is a high-severity denial of service vulnerability in boa-dev boa, published on 15 Aug 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-248
Which versions are affected by CVE-2024-43367?
3 open source packages ship an affected version, including boa_engine.
| Package | Affected | Fixed in |
|---|---|---|
boa_engine crates.io | From 0.16 | 0.19.0 |
boa_engine crates.io | From 0.16 | 0.19.0 |
boa_engine crates.io | From 0.16.0 | 0.19.0 |
How do I fix CVE-2024-43367?
Upgrade boa_engine to 0.19.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-43367 being exploited?
There is no known exploitation of CVE-2024-43367 in the wild and no public exploit code.
Sources
Also known as GHSA-f67q-wr6w-23jq, RUSTSEC-2024-0444.