CVE-2020-5209

Local code execution via unbounded option formatting

Published Jan 28, 2020 · Updated Aug 4, 2024

Buffer overflow in NetHack 3.6.0 through 3.6.4 allows local users to execute code or crash the game via long -de or -i options. The Unix process_options function passes an arbitrarily long unknown option to raw_printf with an unbounded %s conversion, which overflows a fixed local formatting buffer. The flaw is reachable when a local user controls command-line arguments on a shared host; suid or sgid execution exposes the program's effective privileges.

CVSS severity5.0
Medium
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in NetHack 3.6.0 through 3.6.4 allows local users to execute code or crash the game via long -de or -i options. The Unix process_options function passes an arbitrarily long unknown option to raw_printf with an unbounded %s conversion, which overflows a fixed local formatting buffer. The flaw is reachable when a local user controls command-line arguments on a shared host; suid or sgid execution exposes the program's effective privileges.

The record

CVE
CVE-2020-5209
Published
Jan 28, 2020
Updated
Aug 4, 2024
Vendor
NetHack
Product
NetHack
Classifications
CWE-120, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 28, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.6.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

NetHack · NetHackversion=< 3.6.5

Published CVSS scores

5.0GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:L
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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