CVE-2017-17521
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 · unediteduiutil.c in FontForge through 20170731 does not validate strings before launching the program specified by the BROWSER environment variable, which might allow remote attackers to conduct argument-injection attacks via a crafted URL, a different vulnerability than CVE-2017-17534.
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 confidenceuiutil.c in FontForge does not validate strings before launching the program specified by the BROWSER environment variable, allowing argument injection attacks via crafted URLs. An attacker can inject additional command-line arguments when FontForge invokes the browser configured in BROWSER.
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<= 20170731CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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.
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Identify if FontForge is installedRun 'fontforge --version' or check your package manager for fontforge installation statusAffected if FontForge is installed and responds to version query
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Determine the installed FontForge versionCompare the output from 'fontforge --version' or your package manager against the affected range (versions <= 20170731)Affected if The installed version is 20170731 or earlier
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Check if the BROWSER environment variable is setRun 'echo $BROWSER' or inspect environment variables for a BROWSER variableAffected if The BROWSER environment variable is defined and contains a path to an executable or command
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Verify FontForge uses BROWSER for URL handlingInspect uiutil.c source code if available, or test by setting BROWSER to a test script and triggering a URL open action in FontForgeAffected if FontForge invokes the browser via the BROWSER variable without sanitizing arguments
A user is affected if FontForge version 20170731 or earlier is installed AND the BROWSER environment variable is set and used when opening URLs in FontForge.
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 dataValidate and sanitize the BROWSER environment variable and any URL parameters before execution; use an allowlist approach for permitted browser binaries or hardcode safe execution methods; update FontForge if a patched version is available.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-17521 — 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-2017-17521 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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