Vulnerability in Ts-Deepmerge

CVE-2026-12644

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 · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.005 (40.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-12644: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

  • Ts-Deepmerge — versions 0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-12644?
CVE-2026-12644 is a medium-severity vulnerability in Ts-Deepmerge, classified under CWE-248. CVSS score: 5.3/10. Published 2026-06-19.
How severe is CVE-2026-12644?
Medium severity. CVSS v3 base score is 5.3 out of 10.