ts-deepmerge: Prototype Method Override leads to DoS
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | ts-deepmerge | < 8.0.0 | 8.0.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-12644
- https://github.com/voodoocreation/ts-deepmerge/commit/305a05831a462fb2c353d3cbbff55a0733286f8c
- https://gist.github.com/igorg1312/775fa00114c4d47df6ae0551779ab407
- https://github.com/voodoocreation/ts-deepmerge
- https://security.snyk.io/vuln/SNYK-JS-TSDEEPMERGE-17339141
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-248- Platform
- npm
- Package
ts-deepmerge- Disclosed
- 19.06.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-87mf-gv2c-c62c - CC BY 4.0
Vulnerability history: ts-deepmerge
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 08.2022 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- Medium 1
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 1
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