CVE-2020-5253: NetHack before version 3.6.0 allowed malicious use of escaping of characters in the configuration file (usuall

Q: How do I fix CVE-2020-5253?

nethack: upgrade to 3.6.0. Exact commands for each OS are on this page.

Q: Is CVE-2020-5253 being exploited?

CVE-2020-5253 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-5253 affect?

CVE-2020-5253 affects nethack. Severity is low (CVSS 3.9). NetHack before version 3.6.0 allowed malicious use of escaping of characters in the configuration file (usually .nethackrc) which could be exploited. This bug is patched in NetHack 3.6.0.

Q: How urgent is CVE-2020-5253?

Priority 25/100. No elevated risk signals yet.

Routine

LOW 3.9UPGRADE

CVE-2020-5253 is a low-severity flaw (CVSS 3.9) affecting nethack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

NetHack before version 3.6.0 allowed malicious use of escaping of characters in the configuration file (usually .nethackrc) which could be exploited. This bug is patched in NetHack 3.6.0.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	3.9 (Low)
Attack vector	Local
Attack complexity	High
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.5% (top 54%)
CISA exploited list	No
Weakness	CWE-184, CWE-269
Published	2020-03-10
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: nethack

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-03-10 17:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

nethack nethack UPGRADE

Affected: < 3.6.0

Fixed in: 3.6.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nethack || rpm -q nethack || nethack --version

2. UPGRADE to 3.6.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nethack

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nethack

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-5253?

nethack: upgrade to 3.6.0. Exact commands for each OS are on this page.

Is CVE-2020-5253 being exploited?

CVE-2020-5253 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-5253 affect?

CVE-2020-5253 affects nethack. Severity is low (CVSS 3.9). NetHack before version 3.6.0 allowed malicious use of escaping of characters in the configuration file (usually .nethackrc) which could be exploited. This bug is patched in NetHack 3.6.0.

How urgent is CVE-2020-5253?

Priority 25/100. No elevated risk signals yet.

Related CVEs

CVE-2023-24809 MEDIUM 5.5 UPGRADE NetHack is a single player dungeon exploration game
CVE-2020-5254 LOW 3.9 UPGRADE In NetHack before 3.6.6, some out-of-bound values for the hilite_status option can be exploited
CVE-2020-5214 MEDIUM 5.0 UPGRADE In NetHack before 3.6.5, detecting an unknown configuration file option can cause a buffer overflow resulting
CVE-2020-5213 MEDIUM 5.0 UPGRADE In NetHack before 3.6.5, too long of a value for the SYMBOL configuration file option can cause a buffer overf
CVE-2020-5212 MEDIUM 5.0 UPGRADE In NetHack before 3.6.5, an extremely long value for the MENUCOLOR configuration file option can cause a buffe

References

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