CVE-2023-24809: NetHack is a single player dungeon exploration game

Routine

MEDIUM 5.5UPGRADE

CVE-2023-24809 is a medium-severity flaw (CVSS 5.5) affecting nethack. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

NetHack is a single player dungeon exploration game. Starting with version 3.6.2 and prior to version 3.6.7, illegal input to the "C" (call) command can cause a buffer overflow and crash the NetHack process. This vulnerability may be a security issue for systems that have NetHack installed suid/sgid and for shared systems. For all systems, it may result in a process crash. This issue is resolved in NetHack 3.6.7. There are no known workarounds.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-120
Published	2023-02-17
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

2023-02-17 20:15 UTCPublished CVE record published
2026-06-17 05:39 UTCUpdated Record last modified

nethack nethack UPGRADE

Affected: >= 3.6.2 and < 3.6.7

Fixed in: 3.6.7

Safe to downgrade to: a release before 3.6.2

1. Check installed version

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

2. UPGRADE to 3.6.7 (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.

3. If no update is available yet, DOWNGRADE to a release before 3.6.2 (Debian / Ubuntu)

apt-cache madison nethack sudo apt install nethack=<VERSION_BEFORE_3.6.2> sudo apt-mark hold nethack

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nethack sudo dnf downgrade nethack-<VERSION_BEFORE_3.6.2> sudo dnf versionlock add nethack

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2023-24809?

nethack: upgrade to 3.6.7. Exact commands for each OS are on this page.

Is CVE-2023-24809 being exploited?

CVE-2023-24809 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-2023-24809 affect?

CVE-2023-24809 affects nethack. Severity is medium (CVSS 5.5). NetHack is a single player dungeon exploration game. Starting with version 3.6.2 and prior to version 3.6.7, illegal input to the "C" (call) command can cause a buffer overflow and crash the NetHack process. This vulnerability may be a secu

How urgent is CVE-2023-24809?

Priority 23/100. No elevated risk signals yet.

References

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