Answer in brief
CVE-2024-43367 records a High severity (CVSS 8.6) vulnerability in Uncaught exception when transitioning the state of `AsyncGenerator` objects from within a property getter of `then`. The current sources do not mark it as known exploited. The current feed maps boa_engine (crates.io). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps boa_engine (crates.io). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| boa_enginecrates.io | >=0.16.0 <0.19.0 | 0.19.0 |
Published upstream
Aug 14, 2024
Evidence: source:osv:source_dates:source-dates:recordSource modified
Oct 12, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Oct 12, 2026
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.
Quoted source text, attributed separately from HOL analysis.