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XcodeApplication · Apple

CVE-2019-8721

HIGH · 8.8 CVSS v3.1 Published 2019-12-18
Fix available
A fix is available. Upgrade to 11.0 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
Multiple issues in ld64 in the Xcode toolchains were addressed by updating to version ld64-507.4. This issue is fixed in Xcode 11.0. Compiling code without proper input validation could lead to arbitrary code execution with user privilege.

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

A vulnerability in the ld64 linker included with Xcode allows improper input validation during compilation, potentially enabling arbitrary code execution with user privileges. The issue was addressed by updating ld64 to version 507.4 in Xcode 11.0.

MitigationUpdate Xcode to version 11.0 or later to obtain the patched ld64-507.4 linker. Verify that build processes function correctly after the update.

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:< 11.0

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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. Verify Xcode is installed
    Run `xcode-select -p` to check if Xcode command line tools are configured, or check for /Applications/Xcode.app existence
    Affected if Command fails or path does not exist - Xcode is not installed (not vulnerable since the software is absent)
  2. Get Xcode version number
    Run `xcodebuild -version` to retrieve the installed Xcode version
    Affected if Command fails - Xcode may be installed but command line tools are not properly configured
  3. Compare version to affected range
    Compare the reported Xcode version to 11.0. Versions below 11.0 contain the vulnerable ld64 linker
    Affected if Xcode version is less than 11.0 (for example, 10.x) - the environment contains the vulnerable ld64 linker
  4. Alternative: Check ld64 version directly
    Locate ld64 in the Xcode toolchain path (typically at Xcode.app/Contents/Developer/Toolchains/XcodeDefault.toolchain/usr/bin/ld64) and run `ld64 -version`
    Affected if ld64 version is earlier than 507.4 - the linker has the input validation vulnerability

The environment is affected if Xcode version is below 11.0 (or ld64 version is below 507.4), as this indicates the unpatched linker with improper input validation is present.

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 11.0 or later
Fixed in 11.0
Interim mitigation

Update Xcode to version 11.0 or later to obtain the patched ld64-507.4 linker. Verify that build processes function correctly after the update.

Fix this in Xcode Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

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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-2019-8721 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