What is CVE-2023-30087?

CVE-2023-30087 is a medium-severity vulnerability in Cesanta Mjs, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2023-05-09.

How severe is CVE-2023-30087?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Cesanta Mjs

CVE-2023-30087

Buffer Overflow vulnerability found in Cesanta MJS v.1.26 allows a local attacker to cause a denial of service via the mjs_mk_string function in mjs.c.

Vulnerability class: Buffer Overflow

Published 2023-05-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.003 (15.3th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Cesanta Mjs — versions 1.26

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

github.com/cesanta/mjs/issues/244 (Exploit, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2023-30087?: CVE-2023-30087 is a medium-severity vulnerability in Cesanta Mjs, classified under Out-of-bounds Write. CVSS score: 5.5/10. Published 2023-05-09.
How severe is CVE-2023-30087?: Medium severity. CVSS v3 base score is 5.5 out of 10.