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XcodeApplication · Apple

CVE-2019-8840

HIGH · 8.8 CVSS v3.1 Published 2020-10-27
Fix available
A fix is available. Upgrade to 11.3 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

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 · unedited
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in Xcode 11.3. Compiling with untrusted sources may lead to arbitrary code execution with user privileges.

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 confidence

CVE-2019-8840 is an out-of-bounds read vulnerability in Xcode's compiler toolchain (likely in LLVM/Clang) that allows arbitrary code execution when compiling untrusted source code. The vulnerability stems from insufficient bounds checking during compilation, which an attacker could exploit by supplying maliciously crafted source files to be compiled.

MitigationUpdate Xcode to version 11.3 or later. Avoid compiling untrusted or unverified source code in development environments, and implement source code provenance policies in CI/CD pipelines.

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
XcodeApplication
Affected:< 11.3

CVSS 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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Determine installed Xcode version
    Run 'xcodebuild -version' in Terminal, or open Xcode and go to Xcode > About Xcode, or check /Applications/Xcode.app/Contents/version.plist
    Affected if Version shown is below 11.3 (e.g., 11.0, 11.2.x, or any version earlier than 11.3)
  2. Identify compilation source trust status
    Review the source code being compiled: check if it originates from untrusted third parties, unverified repositories, or user-submitted content
    Affected if You are compiling source code from untrusted or unverified sources with an affected Xcode version
  3. Confirm Clang/LLVM toolchain is in use
    Verify the build process uses Xcode's default compiler toolchain (clang, clang++, or swiftc) by examining build logs or project build settings
    Affected if Build system uses Xcode's default Clang/LLVM compilers and Xcode version is below 11.3

You are affected if Xcode version is below 11.3 AND you compile untrusted or maliciously crafted source code with the default compiler toolchain.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 11.3 or later
Fixed in 11.3
Interim mitigation

Update Xcode to version 11.3 or later. Avoid compiling untrusted or unverified source code in development environments, and implement source code provenance policies in CI/CD pipelines.

Fix this in Xcode Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-8840 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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