CVE-2020-5213
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn NetHack before 3.6.5, too long of a value for the SYMBOL configuration file 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 upload their own configuration files. Users should upgrade to NetHack 3.6.5.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceNetHack versions before 3.6.5 contain a buffer overflow vulnerability in the configuration file parser when handling the SYMBOL option. When a user-supplied configuration file contains a SYMBOL value exceeding the expected buffer length, the excess data overflows into adjacent memory, potentially allowing an attacker to overwrite return addresses and achieve code execution with the privileges of the running NetHack process.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 3.6.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify NetHack versionRun 'nethack --version' or check the binary with 'nethack -version', or look for version info in the executable using 'strings' or 'file' commandsAffected if Version is lower than 3.6.5 (e.g., 3.6.4, 3.6.3, etc.)
-
Locate NetHack configuration filesCheck common config file locations: ~/.nethackrc, ~/.config/nethack/, or the directory specified via NETHACKOPTIONS environment variable. Look for any user-editable config files used by NetHackAffected if User-supplied or user-writable configuration files are present and loaded by NetHack
-
Inspect SYMBOL option in configIf a config file exists, open it and search for lines beginning with 'SYMBOL' or 'SYM' followed by charactersAffected if A SYMBOL option is defined in the config file and the value length exceeds the expected buffer size (the exact overflow condition cannot be determined without the specific source)
You are affected if NetHack version is below 3.6.5 AND a user-supplied configuration file containing a SYMBOL option is loaded by the NetHack process.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.6.5
Immediately upgrade NetHack to version 3.6.5 or later. On systems where NetHack is installed with suid/sgid binaries, re-apply the setuid/setgid bits after upgrade. For shared systems that permit user configuration files, restrict or validate user-supplied configs to prevent exploitation.
NetHack 3.6.5
- Upgrade NetHack to version 3.6.5 or later to remediate the buffer overflow vulnerability in the SYMBOL configuration file option.
- If upgrading is not immediately possible, ensure that configuration files are not writable by untrusted users and consider removing suid/sgid privileges from the NetHack binary if not strictly necessary.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-5213 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-5213 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data