CVE-2021-30904
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 sync issue was addressed with improved state validation. This issue is fixed in macOS Monterey 12.0.1. A user's messages may continue to sync after the user has signed out of iMessage.
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 confidenceA sync state validation issue in iMessage on macOS Monterey allowed message synchronization to continue running even after a user signed out of iMessage. The vulnerability stemmed from improper validation of the authentication state before initiating or continuing message sync operations, causing potentially sensitive messages to continue syncing to the device post-logout.
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< 12.0.1CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 installed macOS versionGo to Apple menu > About This Mac and note the version number displayed, or run 'sw_vers -productVersion' in TerminalAffected if The version is below 12.0.1 (for example, 12.0, 11.x, or earlier)
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Verify iMessage account configurationOpen the Messages app and check if an iMessage account is signed in under Messages > Preferences > iMessageAffected if An iMessage account is actively signed in on the system
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Confirm sync activity persistence (optional)Sign out of iMessage via Messages > Preferences > iMessage > Sign Out, then monitor for continued sync activity or network connections from processes related to MessagesAffected if Sync operations continue after signing out (indicating the vulnerability is present and exploitable)
A system is affected by this CVE if it runs macOS versions prior to 12.0.1 AND has an iMessage account configured, because the authentication state validation flaw allows message sync to persist after logout.
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 · scoped12.0.1
Apply macOS Monterey 12.0.1 or later security update, which implements improved state validation to properly terminate message sync when users sign out of iMessage.
macOS Monterey 12.0.1
- Back up your Mac using Time Machine or another backup method before updating
- Go to Apple menu > System Preferences (or System Settings on newer macOS)
- Click on Software Update
- Allow macOS to check for updates
- If macOS Monterey 12.0.1 is available, click Update Now to download and install it
- Restart your Mac when prompted to complete the installation
- After updating, verify the version by clicking Apple menu > About This Mac - it should show version 12.0.1
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 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-2021-30904 — 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-2021-30904 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