QuickJS 0.9.0/3b45d15 catch use after free

Summaryinfo

A vulnerability was found in QuickJS. It has been declared as critical. Affected by this issue is the function catch. The manipulation results in use after free. This vulnerability is cataloged as CVE-2025-62491. The attack may be launched remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in QuickJS. Affected is the function catch. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list). * The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop. * The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason). * If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process. * The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed. * Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list. * Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

The advisory is shared for download at bellard.org. This vulnerability is traded as CVE-2025-62491 since 10/15/2025. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 270721 (Linux Distros Unpatched Vulnerability : CVE-2025-62491), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2025-09-13 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (270721). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• QuickJS

Version

• 0.9.0
• 3b45d15

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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