CVE-2021-1751
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 · uneditedA logic issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave. Mounting a maliciously crafted Samba network share may lead to arbitrary code execution.
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 confidenceA logic issue in macOS Samba mounting functionality allows arbitrary code execution when users mount a maliciously crafted Samba network share. The vulnerability stems from improper state management during the share mounting 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>= 10.14, < 10.14.6>= 10.15, < 10.15.7= 10.14.6= 10.15.7>= 11.0, < 11.2CVSS 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
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/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.
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Identify installed macOS versionRun 'sw_vers -productVersion' in Terminal to get the exact macOS version numberAffected if The version is 10.14.x before 10.14.6, 10.15.x before 10.15.7, or 11.0-11.1 (any version >= 11.0 but < 11.2)
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Confirm macOS name and buildRun 'sw_vers' to see both product version and build version, then compare build against security update builds for your macOS releaseAffected if The system is running an unpatched Mojave, Catalina, or Big Sur 11.0-11.1 version
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Verify Samba mounting capability is presentCheck for the presence of Samba-related system components by examining /usr/lib/samba or looking for the 'mount_smbfs' command: ls -la /sbin/mount_smbfsAffected if The Samba mounting binaries exist on the system (the vulnerability requires this component to be present)
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Check for configured or recent Samba mountsRun 'mount' or 'mount | grep smb' to list currently mounted network shares, and check ~/.smb or /etc/samba/smb.conf if it existsAffected if Any active or configured SMB/Samba mounts are present on the system
A user is affected if they are running macOS Mojave, Catalina, or Big Sur 11.0-11.1 without the Security Update 2021-001 patches and have Samba mounting capability available on their system.
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 data10.14.610.15.711.2
Apply the appropriate macOS security update (Big Sur 11.2, Security Update 2021-001 for Catalina, or Security Update 2021-001 for Mojave) to affected systems. Avoid mounting untrusted or unknown Samba network shares until patches are applied.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1751 — 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-2021-1751 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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