CVE-2026-88378

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.

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.

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.

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.

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.

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.

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.

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.