CVE-2025-62491
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk34th percentile - higher than 34% of all known CVEs
Summary
A use-after-free exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (rejected_promise_list). A malicious property getter on an Error object can call catch() on the same rejected promise, which removes and frees the current list entry while the loop continues using the freed pointer.
Risk Assessment
This can lead to memory corruption and potential code execution in applications embedding QuickJS that process untrusted JavaScript.
Recommendation
Update QuickJS to a version containing the fix and avoid running untrusted JavaScript.
Other vulnerabilities in QuickJS
See all- CVE-2026-88378Critical
QuickJS commit 04be24600 contains a heap out-of-bounds write condition in JS_ReadFunctionTag().
- CVE-2025-12745Medium
In QuickJS up to commit eb2c89087def1829ed99630cb14b549d7a98408c, the function js_array_buffer_slice in quickjs.c causes a buffer over-read. The attack requires local execution, and the exploit is publicly available.
- CVE-2025-62496High
A vulnerability in the QuickJS engine when creating a BigInt from a string with an excessively large number of digits. The bit count calculation causes an integer overflow, leading to an underestimated buffer size and a heap out-of-bounds write.
- CVE-2025-62495High
An integer overflow vulnerability in the QuickJS regular expression engine (libregexp) due to inconsistent representation of the bytecode buffer size. A large or complex regular expression can cause the size to wrap around and lead to an out-of-bounds write.
- CVE-2025-62494High
A type confusion vulnerability exists in the QuickJS engine's handling of the string addition (+) operation. During conversion of the right-hand operand, a callback can change the type of the left-hand operand, leading to a type mismatch and potential out-of-bounds memory access.
- CVE-2025-62493Medium
A vulnerability in the QuickJS engine's BigInt string conversion logic (js_bigint_to_string1) stems from an incorrect calculation of the required number of digits, leading to reading memory past the allocated BigInt structure. In certain edge cases, the conversion loop reads data spanning two limbs, causing an out-of-bounds read.
- CVE-2025-62492Medium
A floating-point arithmetic precision error exists in QuickJS's implementation of TypedArray.prototype.indexOf() when a negative fromIndex argument is supplied. When the value is extremely small (e.g., -1e-20), adding the array length can lose precision and yield an index equal to the length, causing an out-of-bounds read of one element. This may lead to information disclosure of adjacent memory.
- CVE-2025-62490High
In QuickJS's js_print_object, printing an array fetches the length and then loops over it, but printing a value is not side-effect free. An attacker-defined callback can run during js_print_value and resize the array, causing a use-after-free; a second instance occurs when printing Map or Set objects whose records list can be modified during js_print_value.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS