Vulnerability · Published Jul 21, 2026 · Assigned by snyk
CVE-2026-16266
Medium 4.0
In plain English
A medium-severity prototype pollution in mongo-object. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Severity (CVSS 3.1)4.0Medium
Exploit odds (30 days)0.4%top 63.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
Versions of the package mongo-object before 3.0.3 are vulnerable to Prototype Pollution via the expandKey() function in util.js. An attacker can modify the JavaScript prototype chain by supplying a crafted property path containing special keys such as __proto__.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| n/a | mongo-object | 0 – before 3.0.3 |
Weakness: CWE-1321 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
References
- https://security.snyk.io/vuln/SNYK-JS-MONGOOBJECT-13816714
- https://github.com/longshotlabs/mongo-object/issues/27
- https://github.com/longshotlabs/mongo-object/blob/4f7a570f2a2fcfa9417b7870d5f859e9574ec73c/src/util.ts%23L251
- https://github.com/longshotlabs/mongo-object/commit/638314107d8b397e5453c28e41729522b3e8d67c