What’s Vulnerable › Vulnerabilities

CVE-2021-33440

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-07-26 · updated 2026-06-17
• Weakness: CWE-476

Description

An issue was discovered in mjs (mJS: Restricted JavaScript engine), ES6 (JavaScript version 6). There is NULL pointer dereference in mjs_bcode_commit() in mjs.c.

Affected products

• Cesanta mJS: before 2.20.0 — fixed in 2.20.0

How to fix

Upgrade to a fixed version: Cesanta mJS 2.20.0. Check the vendor advisory for mitigations.

References

• https://gist.github.com/Clingto/bb632c0c463f4b2c97e4f65f751c5e6d
• https://github.com/cesanta/mjs/issues/163
• https://gist.github.com/Clingto/bb632c0c463f4b2c97e4f65f751c5e6d
• https://github.com/cesanta/mjs/issues/163

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