CVE-2026-28848: Apple macOS Buffer Overflow Vulnerability

CVE-2026-28848 Overview

CVE-2026-28848 is a stack-based buffer overflow [CWE-121] affecting Apple macOS. A remote attacker can trigger unexpected system termination by sending crafted input that exceeds allocated buffer boundaries. Apple addressed the issue with improved bounds checking in macOS Sequoia 15.7.7 and macOS Tahoe 26.5.

The vulnerability requires no authentication, no user interaction, and is reachable over the network. Successful exploitation impacts system availability but does not compromise confidentiality or integrity according to the CVSS vector.

Critical Impact

Remote unauthenticated attackers can crash macOS systems, resulting in denial of service across affected fleets.

Affected Products

• Apple macOS versions prior to Sequoia 15.7.7
• Apple macOS versions prior to Tahoe 26.5
• Systems exposing the vulnerable network-facing component

Discovery Timeline

• 2026-05-11 - CVE-2026-28848 published to NVD
• 2026-05-12 - Last updated in NVD database

Technical Details for CVE-2026-28848

Vulnerability Analysis

The flaw is classified under [CWE-121] as a stack-based buffer overflow. A network-reachable component in macOS fails to validate the size of incoming data before copying it into a fixed-size stack buffer. When the input exceeds the buffer capacity, adjacent stack memory is overwritten, corrupting saved return addresses or local variables.

The corruption results in unexpected system termination rather than arbitrary code execution. Apple's CVSS assessment scores the issue with high availability impact but no confidentiality or integrity impact. The EPSS score is 0.11% with a percentile of 28.99, indicating low predicted exploitation activity at present.

Apple's advisory states the fix uses improved bounds checking, confirming the root cause was missing or insufficient length validation prior to memory copy operations. The specific affected component is not disclosed in the public advisory.

Root Cause

The vulnerable code path performs a copy operation into a stack-allocated buffer without verifying that the source length fits within the destination. Attacker-controlled input from the network reaches this copy without prior sanitization, allowing the overflow to occur.

Attack Vector

An attacker sends crafted network traffic to a vulnerable macOS host. No credentials or user interaction are required. The malformed payload triggers the overflow, which corrupts stack memory and causes the affected process or the system to terminate.

No public proof-of-concept exploit has been published. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to Apple Support Document #127115 and Apple Support Document #127116 for vendor details.

Detection Methods for CVE-2026-28848

Indicators of Compromise

• Unexpected kernel panics or service crashes on macOS hosts following inbound network traffic
• Crash reports in /Library/Logs/DiagnosticReports/ showing stack corruption signatures
• Repeated reboots or termination events on hosts running macOS versions below 15.7.7 or 26.5

Detection Strategies

• Monitor endpoint telemetry for abnormal process termination events on macOS systems
• Inspect network traffic patterns to identify malformed packets targeting macOS services
• Correlate crash diagnostic reports against the timing of inbound external connections

Monitoring Recommendations

• Forward macOS crash logs and ReportCrash artifacts to a centralized logging platform
• Alert on clusters of macOS system terminations originating from the same source IP
• Track patch compliance for macOS 15.7.7 and macOS 26.5 across managed endpoints

How to Mitigate CVE-2026-28848

Immediate Actions Required

• Update affected hosts to macOS Sequoia 15.7.7 or macOS Tahoe 26.5 without delay
• Inventory all macOS endpoints and servers to identify unpatched systems
• Restrict network exposure of macOS hosts that cannot be patched immediately

Patch Information

Apple released fixes in macOS Sequoia 15.7.7 and macOS Tahoe 26.5. See Apple Support Document #127115 and Apple Support Document #127116 for the complete list of addressed issues and download instructions.

Workarounds

• Block untrusted inbound network access to macOS hosts using a perimeter or host firewall
• Disable or filter the affected network service if business operations permit
• Apply network segmentation to isolate macOS endpoints from untrusted networks until patches are deployed

# Verify installed macOS version on managed endpoints
sw_vers -productVersion

# Enable the macOS application firewall
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on

# Trigger software update check
sudo softwareupdate --install --all --restart