FreeBSDOperating system
CVE-2018-6917
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 FreeBSD before 11.1-STABLE, 11.1-RELEASE-p9, 10.4-STABLE, 10.4-RELEASE-p8 and 10.3-RELEASE-p28, insufficient validation of user-provided font parameters can result in an integer overflow, leading to the use of arbitrary kernel memory as glyph data. Unprivileged users may be able to access privileged kernel data.
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 confidenceIn FreeBSD kernel's font handling subsystem, insufficient validation of user-provided font parameters allows an integer overflow when calculating glyph memory offsets. This enables unprivileged users to read arbitrary kernel memory by specifying malicious font dimensions that overflow bounds checks, exposing privileged kernel data as glyph data.
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
FreeBSDOperating system
>= 10.0, < 10.4>= 11.0, < 11.1CVSS 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
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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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Check FreeBSD kernel versionRun `uname -r` or `freebsd-version -k` to obtain the running kernel versionAffected if Version is >= 10.0 and < 10.4, OR >= 11.0 and < 11.1
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Verify font subsystem accessCheck for presence of font-related device nodes such as /dev/fb or /dev/vt*, or observe if programs can invoke font-related ioctl callsAffected if The font handling subsystem is accessible to unprivileged users (typical default configuration)
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Confirm unprivileged user accessAttempt to use a program or utility that passes custom font dimensions to the kernel (e.g., framebuffer or console font utilities) as a non-root userAffected if User-space programs can pass font parameters to the kernel without privilege escalation
The system is affected if it runs a FreeBSD kernel version within 10.0 to 10.3, 10.4 before p8, or 11.0 to 11.1 before p9, and the kernel font handling subsystem is accessible to unprivileged users.
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 data10.411.1
Upgrade FreeBSD systems to 11.1-STABLE, 11.1-RELEASE-p9 or later, 10.4-STABLE, 10.4-RELEASE-p8 or later, or 10.3-RELEASE-p28 or later to receive the patched kernel, then reboot into the patched kernel.
Fix this in FreeBSD
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 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 $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-6917 — 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-2018-6917 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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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