CVE-2024-43357
JavaScript specification issue may lead to type confusion and pointer dereference in implementations
ECMA-262 is the language specification for the scripting language ECMAScript. A problem in the ECMAScript (JavaScript) specification of async generators, introduced by a May 2021 spec refactor, may lead to mis-implementation in a way that could present as a security vulnerability, such as type confusion and pointer dereference.
The internal async generator machinery calls regular promise resolver functions on IteratorResult ({ done, value }) objects that it creates, assuming that the IteratorResult objects will not be then-ables. Unfortunately, these IteratorResult objects inherit from Object.prototype, so these IteratorResult objects can be made then-able, triggering arbitrary behaviour, including re-entering the async generator machinery in a way that violates some internal invariants.
The ECMAScript specification is a living standard and the issue has been addressed at the time of this advisory's public disclosure. JavaScript engine implementors should refer to the latest specification and update their implementations to comply with the AsyncGenerator section.
References
- https://github.com/tc39/ecma262/commit/1e24a286d0a327d08e1154926b3ee79820232727
- https://bugzilla.mozilla.org/show_bug.cgi?id=1901411
- https://github.com/boa-dev/boa/security/advisories/GHSA-f67q-wr6w-23jq
- https://bugs.webkit.org/show_bug.cgi?id=275407
- https://issues.chromium.org/issues/346692561
- https://www.cve.org/CVERecord?id=CVE-2024-7652
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
JavaScript specification issue may lead to type confusion and pointer dereference in implementations
ECMA-262 is the language specification for the scripting language ECMAScript. A problem in the ECMAScript (JavaScript) specification of async generators, introduced by a May 2021 spec refactor, may lead to mis-implementation in a way that could present as a security vulnerability, such as type confusion and pointer dereference.
The internal async generator machinery calls regular promise resolver functions on IteratorResult ({ done, value }) objects that it creates, assuming that the IteratorResult objects will not be then-ables. Unfortunately, these IteratorResult objects inherit from Object.prototype, so these IteratorResult objects can be made then-able, triggering arbitrary behaviour, including re-entering the async generator machinery in a way that violates some internal invariants.
The ECMAScript specification is a living standard and the issue has been addressed at the time of this advisory's public disclosure. JavaScript engine implementors should refer to the latest specification and update their implementations to comply with the AsyncGenerator section.
References
- https://github.com/tc39/ecma262/commit/1e24a286d0a327d08e1154926b3ee79820232727
- https://bugzilla.mozilla.org/show_bug.cgi?id=1901411
- https://github.com/boa-dev/boa/security/advisories/GHSA-f67q-wr6w-23jq
- https://bugs.webkit.org/show_bug.cgi?id=275407
- https://issues.chromium.org/issues/346692561
- https://www.cve.org/CVERecord?id=CVE-2024-7652
- Record
CVE-2024-43357- CVSS 3.1
- 8.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-248, CWE-476, CWE-843
- Updated
- 2026-11-02
EUVDEUVD-2024-40246
ECMA-262 is the language specification for the scripting language ECMAScript. A problem in the ECMAScript (JavaScript) specification of async generators, introduced by a May 2021 spec refactor, may lead to mis-implementation in a way that could present as a security vulnerability, such as type confusion and pointer dereference.
The internal async generator machinery calls regular promise resolver functions on IteratorResult ({ done, value }) objects that it creates, assuming that the IteratorResult objects will not be then-ables. Unfortunately, these IteratorResult objects inherit from Object.prototype, so these IteratorResult objects can be made then-able, triggering arbitrary behaviour, including re-entering the async generator machinery in a way that violates some internal invariants.
The ECMAScript specification is a living standard and the issue has been addressed at the time of this advisory's public disclosure. JavaScript engine implementors should refer to the latest specification and update their implementations to comply with the AsyncGenerator section.
References
- https://github.com/tc39/ecma262/commit/1e24a286d0a327d08e1154926b3ee79820232727
- https://bugzilla.mozilla.org/show_bug.cgi?id=1901411
- https://github.com/boa-dev/boa/security/advisories/GHSA-f67q-wr6w-23jq
- https://bugs.webkit.org/show_bug.cgi?id=275407
- https://issues.chromium.org/issues/346692561
- https://www.cve.org/CVERecord?id=CVE-2024-7652
- Record
EUVD-2024-40246- CVSS 3.1
- 8.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Updated
- 2026-11-03
NVD
ECMA-262 is the language specification for the scripting language ECMAScript. A problem in the ECMAScript (JavaScript) specification of async generators, introduced by a May 2021 spec refactor, may lead to mis-implementation in a way that could present as a security vulnerability, such as type confusion and pointer dereference.
The internal async generator machinery calls regular promise resolver functions on IteratorResult ({ done, value }) objects that it creates, assuming that the IteratorResult objects will not be then-ables. Unfortunately, these IteratorResult objects inherit from Object.prototype, so these IteratorResult objects can be made then-able, triggering arbitrary behaviour, including re-entering the async generator machinery in a way that violates some internal invariants.
The ECMAScript specification is a living standard and the issue has been addressed at the time of this advisory's public disclosure. JavaScript engine implementors should refer to the latest specification and update their implementations to comply with the AsyncGenerator section.
References
- https://github.com/tc39/ecma262/commit/1e24a286d0a327d08e1154926b3ee79820232727
- https://bugzilla.mozilla.org/show_bug.cgi?id=1901411
- https://github.com/boa-dev/boa/security/advisories/GHSA-f67q-wr6w-23jq
- https://bugs.webkit.org/show_bug.cgi?id=275407
- https://issues.chromium.org/issues/346692561
- https://www.cve.org/CVERecord?id=CVE-2024-7652
- Record
CVE-2024-43357- CVSS 3.1
- 8.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-248, CWE-476, CWE-843
- Updated
- 2026-11-02
OSV
JavaScript specification issue may lead to type confusion and pointer dereference in implementations
ECMA-262 is the language specification for the scripting language ECMAScript. A problem in the ECMAScript (JavaScript) specification of async generators, introduced by a May 2021 spec refactor, may lead to mis-implementation in a way that could present as a security vulnerability, such as type confusion and pointer dereference.
The internal async generator machinery calls regular promise resolver functions on IteratorResult ({ done, value }) objects that it creates, assuming that the IteratorResult objects will not be then-ables. Unfortunately, these IteratorResult objects inherit from Object.prototype, so these IteratorResult objects can be made then-able, triggering arbitrary behaviour, including re-entering the async generator machinery in a way that violates some internal invariants.
The ECMAScript specification is a living standard and the issue has been addressed at the time of this advisory's public disclosure. JavaScript engine implementors should refer to the latest specification and update their implementations to comply with the AsyncGenerator section.
References
- https://github.com/tc39/ecma262/commit/1e24a286d0a327d08e1154926b3ee79820232727
- https://bugzilla.mozilla.org/show_bug.cgi?id=1901411
- https://github.com/boa-dev/boa/security/advisories/GHSA-f67q-wr6w-23jq
- https://bugs.webkit.org/show_bug.cgi?id=275407
- https://issues.chromium.org/issues/346692561
- https://www.cve.org/CVERecord?id=CVE-2024-7652
- Record
CVE-2024-43357- CVSS 3.1
- 8.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-248, CWE-476, CWE-843
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-43357 is a high vulnerability (CVSS 8.6) in Ecma International Ecma262, published August 15, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.68%, the 52nd percentile. No source names a fixed version.
References
github.com/tc39/ecma262/security/advisories/GHSA-g38c-wh3c-5h9r
bugs.webkit.org/show_bug.cgi?id=275407