CVE-2025-62491: Use-after-free in js_std_promise_rejection_check in QuickJS

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->rejectedpromiselist).

The function jsstdpromiserejectioncheck attempts to iterate over the rejectedpromiselist to report unhandled rejections using a standard list loop.

The reason for a promise rejection is processed inside the loop, including calling jsstddumperror1(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 jsstdpromiserejectiontracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejectedpromiselist.

Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.