CVE-2025-62490: Use-after-free in js_print_object in QuickJS

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-10-16 · updated 2026-10-19
Weakness: CWE-416

Description

In quickjs, in js_print_object, when printing an array, the function first fetches the array length and then loops over it. The issue is, printing a value is not side-effect free. An attacker-defined callback could run during js_print_value, during which the array could get resized and len1 become out of bounds. This results in a use-after-free.A second instance occurs in the same function during printing of a map or set objects. The code iterates over ms->records list, but once again, elements could be removed from the list during js_print_value call.

Affected products

QuickJS: before 2025-09-13 — fixed in 2025-09-13

How to fix

Upgrade to a fixed version: QuickJS 2025-09-13. Check the vendor advisory for mitigations.

References

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