CVE-2018-12270
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 Valve Steam 1528829181 BETA, it is possible to perform a homograph / homoglyph attack to create fake URLs in the client, which may trick users into visiting unintended web sites.
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 · moderate confidenceThis is a URL spoofing vulnerability in the Steam client where homograph/homoglyph attacks can be used to create deceptive URLs. Attackers exploit visually similar characters from different scripts (e.g., Cyrillic 'a' vs Latin 'a') to make malicious URLs appear as legitimate sites, potentially tricking users into visiting unintended websites.
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= 1528829181CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
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.
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Identify installed Steam client versionLocate the Steam installation directory (default: C:\Program Files\Steam or C:\Program Files (x86)\Steam). Open the clientregistry.blob file in a text editor or use Steam's built-in version info by clicking on your username in the client and selecting 'Settings' > 'About Steam', or run 'steam.exe -ver' from command line if supported.Affected if The displayed version/build number equals exactly 1528829181
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Compare version to affected buildCompare the installed Steam build number to the affected version 1528829181. Build numbers are typically shown as large integers in Steam's About dialog.Affected if The installed version is exactly 1528829181 (no other versions are listed as affected in the provided CVE data)
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Test URL display for internationalized domain namesIn the Steam client, attempt to open or hover over a link containing internationalized domain names with lookalike characters (e.g., Cyrillic 'a' (U+0430) replacing Latin 'a' (U+0061) in a known domain). Observe whether the client displays the Punycode representation (xn--...) or the raw Unicode characters.Affected if The Steam client displays the raw Unicode internationalized domain name without converting to Punycode, making visually deceptive URLs appear legitimate
You are affected if your Steam client build is exactly 1528829181 and URLs with internationalized characters display without Punycode conversion, allowing homograph attacks to succeed.
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.
From vendor dataThe fix requires implementing proper URL validation and display controls in the Steam client, including displaying Punycode for internationalized domain names and validating/filtering lookalike characters to prevent homograph attacks.
- Consultation4.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-12270 — 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-2018-12270 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
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- 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
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