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CVE-2026-12644 voodoocreation CVE debrief

CVE-2026-12644 is a vulnerability in ts-deepmerge, a package used for deep merging objects in TypeScript. Versions before 8.0.0 are susceptible to an Uncaught Exception due to improper handling of built-in Object.prototype methods such as toString and valueOf. When user-controlled input contains these keys with non-function values, the resulting merged object becomes broken, causing any string context operation to throw a TypeError and crash the application.

Vendor
voodoocreation
Product
ts-deepmerge
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-19
Original CVE updated
2026-06-23
Advisory published
2026-06-19
Advisory updated
2026-06-23

Who should care

Developers and security teams using ts-deepmerge in their applications should be aware of this vulnerability. The vulnerability has a CVSS score of 5.5 and a severity of MEDIUM, indicating a moderate risk.

Technical summary

The vulnerability arises from ts-deepmerge's handling of Object.prototype methods. When merging objects, the package does not properly handle built-in methods like toString and valueOf. If user-controlled input includes these keys with non-function values, the merged object becomes malformed. Subsequent string operations on this object will throw a TypeError, leading to application crashes. This issue was addressed in version 8.0.0 of ts-deepmerge.

Defensive priority

Apply patches or upgrade to ts-deepmerge version 8.0.0 or later to mitigate this vulnerability. Review and validate user-controlled input to prevent malicious data from being merged.

Recommended defensive actions

  • Upgrade to ts-deepmerge version 8.0.0 or later
  • Validate and sanitize user-controlled input
  • Implement error handling for potential TypeErrors
  • Monitor applications for crashes related to string operations
  • Perform a thorough review of the application’s codebase to identify and address any similar issues
  • Ensure that all user-controlled input is properly validated and sanitized before being used in object merging
  • Consider implementing additional logging and monitoring to detect potential attacks

Evidence notes

The CVE record was published on 2026-06-19T06:17:01.640Z and was last modified on 2026-06-23T15:42:30.483Z. The NVD entry is currently Deferred. The vulnerability was reported by [email protected] and has a CVSS score of 5.5 with a severity of MEDIUM.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-12644 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-12644

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-12644 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-12644

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.