CVE-2020-7777: Arbitrary Code Execution

Severity: medium (CVSS 6.5 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-11-23 · updated 2026-06-17

Description

This affects all versions of package jsen. If an attacker can control the schema file, it could run arbitrary JavaScript code on the victim machine. In the module description and README file there is no mention about the risks of untrusted schema files, so I assume that this is applicable. In particular the required field of the schema is not properly sanitized. The resulting string that is build based on the schema definition is then passed to a Function.apply();, leading to an Arbitrary Code Execution.

Affected products

jsen: all versions

References

https://github.com/bugventure/jsen/blob/master/lib/jsen.js%23L875
https://snyk.io/vuln/SNYK-JS-JSEN-1014670
https://github.com/bugventure/jsen/blob/master/lib/jsen.js%23L875
https://snyk.io/vuln/SNYK-JS-JSEN-1014670

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