Use-after-free in js_std_promise_rejection_check in QuickJS

Summary

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.

Timeline

1. Oct 16, 2025, 3:51 PM UTCCVE published
2. Oct 16, 2025, 6:03 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: total

3. Oct 16, 2025, 6:04 PM UTCRecord last updated

Affected versions

• js_std_promise_rejection_check

  From 2025-04-26 · fixed in 2025-09-13

References 2