BaseFortify

Publication date: 2025-10-16

Last updated on: 2025-10-30

Assigner: Google Inc.

Description

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.

CVSS Scores

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Meta Information

Published

2025-10-16

Last Modified

2025-10-30

Generated

2026-07-06

AI Q&A

2025-10-16

EPSS Evaluated

2026-07-05

NVD

CVE-2025-62491

Affected Vendors & Products

Vendor	Product	Version / Range
quickjs_project	quickjs	to 2025-09-13 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This vulnerability is a Use-After-Free (UAF) issue in the QuickJS engine's standard library. It occurs when iterating over the global list of unhandled rejected promises. During iteration, if a promise rejection reason has a custom property getter that executes JavaScript code calling catch() on the same rejected promise, the promise entry is removed and freed from the list. However, the iteration continues using the freed memory pointer, causing a Use-After-Free condition.

Impact Analysis

The Use-After-Free vulnerability can lead to undefined behavior such as crashes, memory corruption, or potentially arbitrary code execution within applications using the QuickJS engine. This can compromise application stability and security, possibly allowing attackers to execute malicious code or cause denial of service.

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