What is CVE-2018-20304?

CVE-2018-20304 is a medium-severity vulnerability in Libexcel Project, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 6.5/10. Published 2018-12-20.

How severe is CVE-2018-20304?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Buffer overflow in Libexcel Project

CVE-2018-20304

wbook_addworksheet in workbook.c in libexcel.a in libexcel 0.01 allows attackers to cause a denial of service (SEGV) via a long second argument. NOTE: this is not a Microsoft product.

Vulnerability class: Buffer Overflow

Published 2018-12-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.0th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.0% 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

Libexcel Project — versions 0.01

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

github.com/devinsmith/libexcel/issues/9 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2018-20304?: CVE-2018-20304 is a medium-severity vulnerability in Libexcel Project, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 6.5/10. Published 2018-12-20.
How severe is CVE-2018-20304?: Medium severity. CVSS v3 base score is 6.5 out of 10.