CVE-2025-43505: Apple Xcode Buffer Overflow Vulnerability

CVE-2025-43505 Overview

CVE-2025-43505 is an out-of-bounds write vulnerability in Apple Xcode that can lead to heap corruption. Apple addressed the issue with improved input validation in Xcode 26.1. Processing a maliciously crafted file triggers the flaw, enabling attackers to corrupt heap memory in the affected process.

The weakness is tracked under [CWE-787] (Out-of-bounds Write) and carries a CVSS 3.1 score of 8.8. Exploitation requires user interaction, such as opening or processing a crafted project file in Xcode. Apple published the fix in its support advisory for Xcode 26.1.

Critical Impact

Successful exploitation can corrupt the heap, leading to arbitrary code execution within the context of the Xcode process on developer workstations.

Affected Products

• Apple Xcode versions prior to 26.1
• macOS development environments running vulnerable Xcode builds
• Build pipelines and CI systems that invoke vulnerable Xcode toolchains

Discovery Timeline

• 2025-11-04 - CVE-2025-43505 published to NVD
• 2025-11-04 - Last updated in NVD database
• Patch availability - Fixed in Xcode 26.1 per Apple Support Article

Technical Details for CVE-2025-43505

Vulnerability Analysis

The vulnerability is an out-of-bounds write in Apple Xcode. When Xcode parses a maliciously crafted file, it writes data beyond the bounds of an allocated heap buffer. This heap corruption can overwrite adjacent metadata or object pointers within the process.

Attackers who control the layout of nearby heap allocations can convert the corruption into arbitrary code execution. The bug class [CWE-787] is a frequent root cause of code execution in file parsers. Apple resolved the flaw by adding improved input validation to the affected parsing path.

Because Xcode runs with the privileges of the developer, successful exploitation grants the attacker access to source code, signing keys, and build artifacts on the host.

Root Cause

The root cause is missing or insufficient bounds checking when Xcode processes attacker-supplied file content. The parser writes data to a heap buffer without validating that the input length fits within the allocation. Apple's fix introduces stricter input validation to ensure write operations remain within allocated bounds.

Attack Vector

The attack vector is network-reachable with required user interaction. An attacker delivers a crafted project, workspace, or asset file to a target developer through email, messaging, repository cloning, or supply-chain channels. When the developer opens the file in a vulnerable Xcode version, the parser triggers the out-of-bounds write. No prior privileges or authentication are needed.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-43505

Indicators of Compromise

• Unexpected Xcode process crashes referencing heap corruption or malloc errors in Console.app or crash reports under ~/Library/Logs/DiagnosticReports/
• Xcode spawning unusual child processes such as shells, curl, osascript, or unsigned binaries
• Outbound network connections originating from the Xcode process to untrusted hosts
• Modifications to developer keychains, signing identities, or build scripts shortly after opening third-party project files

Detection Strategies

• Inventory installed Xcode versions across developer endpoints and flag any host running a version earlier than 26.1
• Monitor for crash reports identifying Xcode with signals such as SIGSEGV or SIGABRT combined with heap-related stack frames
• Alert on Xcode process executions that load project files originating from untrusted external sources or recently cloned repositories

Monitoring Recommendations

• Enable endpoint telemetry on macOS developer workstations to capture process lineage, file opens, and network connections from Xcode.app
• Forward Xcode and xcodebuild crash diagnostics to a central logging platform for correlation
• Review CI/CD runners that execute xcodebuild against third-party inputs for anomalous process behavior

How to Mitigate CVE-2025-43505

Immediate Actions Required

• Upgrade all instances of Apple Xcode to version 26.1 or later on developer workstations and build servers
• Restrict opening of untrusted Xcode project, workspace, and asset files until patches are deployed
• Audit CI/CD pipelines that invoke xcodebuild and ensure runners use a patched Xcode toolchain
• Validate the integrity of recently built artifacts and signing materials on hosts that may have processed untrusted files

Patch Information

Apple fixed CVE-2025-43505 in Xcode 26.1. The fix introduces improved input validation in the affected file-processing path to prevent the out-of-bounds write. Refer to the Apple Support Article for the official advisory and download instructions through the Mac App Store or the Apple Developer portal.

Workarounds

• Avoid opening Xcode project files, workspaces, or asset bundles received from untrusted sources
• Use a non-privileged macOS user account dedicated to evaluating third-party Xcode projects
• Inspect third-party projects in a read-only manner with text editors before opening them in Xcode

# Verify the installed Xcode version on macOS
xcodebuild -version

# Switch to a patched Xcode installation if multiple versions are present
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer