CVE-2025-43276
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 error was addressed with improved error handling. This issue is fixed in macOS Sequoia 15.6. iCloud Private Relay may not activate when more than one user is logged in at the same time.
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 confidenceiCloud Private Relay fails to activate when multiple users are logged into the same macOS device simultaneously due to a logic error in error handling. This is a functional bug in macOS Sequoia 15.5 and earlier that prevents the privacy feature from working correctly in multi-user environments.
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< 15.6CVSS 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
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 the installed macOS versionRun 'sw_vers -productVersion' in Terminal or go to System Settings > AboutAffected if The version is 15.5 or earlier (below 15.6)
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Verify iCloud Private Relay is configuredOpen System Settings > Apple ID > iCloud and look for the Private Relay toggle, or check for the presence of 'com.apple.net.ip.personalization' in ~/Library/Preferences/com.apple.iCloud.plistAffected if Private Relay is enabled or has been attempted to be enabled on the system
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Identify multiple active user sessionsRun 'who' in Terminal to show logged-in users, or check Activity Monitor > User for multiple loginwindow processesAffected if More than one user account shows an active session (either via screen sharing, fast user switching, or local console)
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Confirm Private Relay failure in multi-user contextAttempt to enable Private Relay while another user is logged in via fast user switching or screen sharing, then check /var/log/system.log for relay-related errors using 'sudo log show --predicate "subsystem == \"com.apple.net.ip\"" --last 5m'Affected if Private Relay fails to activate or shows errors when multiple users are present
The environment is affected if running macOS below 15.6 with iCloud Private Relay enabled while multiple users are logged in simultaneously.
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 · scoped15.6
Update to macOS Sequoia 15.6 or later to receive the fix for the logic error affecting iCloud Private Relay activation in multi-user sessions.
macOS Sequoia 15.6
- Back up important data before updating
- Open System Settings on your Mac
- Click on General in the sidebar
- Click on Software Update
- Wait for macOS 15.6 to appear and click Update Now or Upgrade Now
- Follow the on-screen instructions to complete the installation
- Restart your Mac if prompted
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-43276 — 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-2025-43276 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
- No spam, self-promotion, credentials, or personal data