What is CVE-2020-23257?

CVE-2020-23257 is a high-severity vulnerability in Espruino, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 7.5/10. Published 2023-04-04.

How severe is CVE-2020-23257?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Espruino

CVE-2020-23257

Buffer Overflow vulnerability found in Espruino 2v05.41 allows an attacker to cause a denial of service via the function jsvGarbageCollectMarkUsed in file src/jsvar.c.

Vulnerability class: Buffer Overflow

Published 2023-04-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.2th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Espruino — versions 2.05.41

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

github.com/espruino/Espruino/issues/1820 (Exploit, Issue Tracking)
www.espruino.com/ (Vendor Advisory)

Frequently asked questions

What is CVE-2020-23257?: CVE-2020-23257 is a high-severity vulnerability in Espruino, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 7.5/10. Published 2023-04-04.
How severe is CVE-2020-23257?: High severity. CVSS v3 base score is 7.5 out of 10.