CVE-2026-12644

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

Versions of the package ts-deepmerge before 8.0.0 are vulnerable to Uncaught Exception due to the improper handling of built-in Object.prototype methods (such as toString, valueOf). When user-controlled input contains these keys with non-function values, the resulting merged object becomes broken — any string context operation throws a TypeError, crashing the application.

Published 2026-06-19. Last modified 2026-06-23.