What is CVE-2020-5210?

CVE-2020-5210 is a medium-severity vulnerability in Nethack, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.0/10. Published 2020-01-28.

How severe is CVE-2020-5210?

Medium severity. CVSS v3 base score is 5.0 out of 10.

Buffer overflow in Nethack

CVE-2020-5210

In NetHack before 3.6.5, an invalid argument to the -w command line option can cause a buffer overflow resulting in a crash or remote code execution/privilege escalation. This vulnerability affects systems that have NetHack installed suid/sgid and shared systems that allow users to influence command line options. Users should upgrade to NetHack 3.6.5.

Vulnerability class: Buffer Overflow

Published 2020-01-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.008 (54.9th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 54.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Nethack — versions < 3.6.5

Weakness classification (CWE)

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

References

github.com/NetHack/NetHack/security/advisories/GHSA-v5pg-hpjg-9rpp (Third Party Advisory)
github.com/NetHack/NetHack/commit/f3def5c0b999478da2d0a8f0b6a7c370a2065f77 (Patch)

Frequently asked questions

What is CVE-2020-5210?: CVE-2020-5210 is a medium-severity vulnerability in Nethack, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.0/10. Published 2020-01-28.
How severe is CVE-2020-5210?: Medium severity. CVSS v3 base score is 5.0 out of 10.