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VulnerabilityPublished Updated

CVE-2026-12644: ts-deepmerge · Uncaught Exception

Affects ts-deepmergeSource CVE Database V5

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Public exploit available · CVSS 6.9 Medium : upgrade to 8.0.0 as a priority.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 8.0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Upgrade ts-deepmerge to 8.0.0.

Affected software

ProductAffectedFixed in
ts-deepmergeAffected
  • <8.0.0
Fixed in
  • 8.0.0
npmts-deepmergepkg:npm/ts-deepmergeOther threatsAffected
  • <8.0.0
Fixed in
  • 8.0.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, avoid merging user-controlled input that may contain Object.prototype keys such as toString or valueOf with non-function values. Implement input validation or sanitization to prevent such keys from being processed by ts-deepmerge.

Description

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.

References

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