CVE-2026-20639
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 · uneditedAn integer overflow was addressed with improved input validation. This issue is fixed in macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, macOS Tahoe 26.3. Processing a maliciously crafted string may lead to heap corruption.
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 confidenceInteger overflow in macOS string processing components allows a maliciously crafted string to overflow integer boundaries during parsing, corrupting the heap. This is a memory corruption vulnerability in the operating system's string handling code.
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>= 14.0, < 14.8.5>= 15.0, < 15.7.5>= 26.0, < 26.3CVSS 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
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Check installed macOS versionRun 'sw_vers -productVersion' in Terminal or go to Apple menu > About This Mac to see the exact version numberAffected if The version is 14.0 to 14.8.4 (Sonoma), 15.0 to 15.7.4 (Sequoia), or 26.0 to 26.2 (Tahoe)
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Verify the full version stringRun 'system_profiler SPSoftwareDataType' in Terminal to get detailed version information including the build numberAffected if The displayed version falls within any of the vulnerable ranges listed
You are affected if your macOS version is any build between 14.0 and 14.8.4, between 15.0 and 15.7.4, or between 26.0 and 26.2.
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 · scoped14.8.515.7.526.3
Apply the relevant macOS security update (Sequoia 15.7.5, Sonoma 14.8.5, or Tahoe 26.3) to patch the vulnerability.
macOS Sonoma 14.8.5+, macOS Sequoia 15.7.5+, or macOS Tahoe 26.3+ depending on your current version
- Back up your Mac using Time Machine or another backup solution before performing the upgrade
- Determine your current macOS version by clicking the Apple menu > About This Mac
- If running macOS Sonoma (14.x), upgrade to macOS Sonoma 14.8.5 or later via System Settings > Software Update
- If running macOS Sequoia (15.x), upgrade to macOS Sequoia 15.7.5 or later via System Settings > Software Update
- If running macOS Tahoe (26.x), upgrade to macOS Tahoe 26.3 or later via System Settings > Software Update
- Restart your Mac when prompted to complete the installation
- Verify the upgrade was successful by checking the macOS version in About This Mac
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 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-2026-20639 — 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-2026-20639 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