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Boa has an uncaught exception when transitioning the state of `AsyncGenerator` objects

High severity GitHub Reviewed Published Aug 14, 2024 in boa-dev/boa • Updated Aug 15, 2024

Package

cargo boa_engine (Rust)

Affected versions

>= 0.16, < 0.19.0

Patched versions

0.19.0

Description

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.

References

References

@jasonwilliams jasonwilliams published to boa-dev/boa Aug 14, 2024
Published to the GitHub Advisory Database Aug 14, 2024
Reviewed Aug 14, 2024
Published by the National Vulnerability Database Aug 15, 2024
Last updated Aug 15, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(44th percentile)

Weaknesses

Uncaught Exception

An exception is thrown from a function, but it is not caught. Learn more on MITRE.

CVE ID

CVE-2024-43367

GHSA ID

GHSA-f67q-wr6w-23jq

Source code

Credits

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