CVE-2026-40345: rebeccastevens deepmerge-ts Uncontrolled Recursion

Vulnerability summary

CVE-2026-40345 is a high (CVSS 8.2) Uncontrolled Recursion vulnerability in rebeccastevens deepmerge-ts. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 43.5% of scored vulnerabilities.

Timeline

1. 20-08-2026
   PublishedVulnerability first disclosed.
2. 21-08-2026
   Last modifiedVulnerability information updated.

Description

deepmerge-ts is a typescript library providing functionality to deep merging of javascript objects. Prior to 8.0.0, the deepmerge, deepmergeCustom, deepmergeInto, and deepmergeIntoCustom APIs do not track visited objects or object pairs when recursively merging records. When two input values contain self-references at the same property path, the merge logic repeatedly revisits the same pair until Node.js raises RangeError: Maximum call stack size exceeded. Applications that merge attacker-controlled recursive object graphs can synchronously crash the affected process or cause repeated worker restarts. Plain JSON input alone cannot create the recursive graph required to trigger the issue. This issue is fixed in version 8.0.0.

• CWE-674Uncontrolled RecursionThe product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.