CVE-2025-31246: Apple macOS Buffer Overflow Vulnerability

CVE-2025-31246 Overview

CVE-2025-31246 is a kernel memory corruption vulnerability affecting Apple macOS that can be triggered when connecting to a malicious Apple Filing Protocol (AFP) server. The vulnerability stems from improper memory handling within the macOS kernel, which can lead to memory corruption when processing specially crafted responses from a malicious AFP server. This issue was addressed by Apple with improved memory handling in macOS Sequoia 15.5 and macOS Sonoma 14.7.6.

Critical Impact

Connecting to a malicious AFP server may corrupt kernel memory, potentially enabling attackers to achieve code execution at the kernel level, escalate privileges, or cause system instability.

Affected Products

• Apple macOS Sequoia (versions prior to 15.5)
• Apple macOS Sonoma (versions prior to 14.7.6)

Discovery Timeline

• 2025-05-12 - CVE-2025-31246 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-31246

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating that the macOS kernel fails to properly validate or restrict memory operations when handling AFP protocol communications. When a macOS system connects to a malicious AFP server, the attacker-controlled server can send specially crafted responses that exploit the memory handling flaw, leading to kernel memory corruption.

The network-based attack vector means that an attacker must entice or trick a user into connecting to their malicious AFP server, or compromise an existing AFP server that the victim connects to. Once connected, the malicious server can exploit the vulnerability without requiring additional user interaction.

Kernel memory corruption vulnerabilities are particularly severe because the kernel operates with the highest privileges on the system. Successful exploitation could allow an attacker to execute arbitrary code with kernel privileges, bypass security controls, access sensitive data, or cause system crashes and denial of service.

Root Cause

The root cause of CVE-2025-31246 lies in improper memory handling within the AFP client implementation in the macOS kernel. When processing data received from an AFP server, the kernel code does not adequately validate input or properly manage memory boundaries. This allows a malicious server to send crafted data that corrupts kernel memory structures, potentially leading to arbitrary code execution or system instability.

Attack Vector

The attack leverages the network-based AFP protocol, which is traditionally used for file sharing between Apple devices. The attack scenario involves:

1. An attacker sets up a malicious AFP server with exploit code designed to trigger the memory corruption
2. The victim's macOS system connects to the malicious AFP server (through social engineering, DNS hijacking, or compromising a legitimate server)
3. During the connection or file operations, the malicious server sends specially crafted responses
4. The macOS kernel improperly handles these responses, resulting in memory corruption
5. The attacker can potentially leverage this corruption for code execution at the kernel level

The vulnerability manifests in the AFP protocol handling layer of the macOS kernel. For detailed technical information, refer to the Apple Security Advisory #122716 and Apple Security Advisory #122717.

Detection Methods for CVE-2025-31246

Indicators of Compromise

• Unexpected AFP connections to unknown or suspicious servers in network logs
• Kernel panic events or system crashes occurring during AFP file operations
• Unusual kernel-level activity or memory access violations logged in system diagnostics
• Connections to AFP servers with unusual hostnames or IP addresses

Detection Strategies

• Monitor network traffic for AFP protocol connections (TCP port 548) to untrusted or unknown destinations
• Implement endpoint detection rules to alert on kernel memory corruption symptoms such as unexpected crashes or panic logs
• Deploy SentinelOne's behavioral AI to detect anomalous kernel activity patterns associated with memory corruption exploits
• Review system logs for AFP-related errors or crashes in /var/log/system.log and crash reports

Monitoring Recommendations

• Configure network security monitoring to track and alert on outbound AFP connections
• Enable verbose logging for AFP client activity where possible
• Utilize SentinelOne Singularity platform to monitor kernel-level activities and detect exploitation attempts
• Implement network segmentation to restrict AFP connections to trusted internal servers only

How to Mitigate CVE-2025-31246

Immediate Actions Required

• Update macOS Sequoia to version 15.5 or later immediately
• Update macOS Sonoma to version 14.7.6 or later immediately
• Disable AFP client functionality if not required for business operations
• Block outbound connections to untrusted AFP servers at the network firewall level
• Audit and inventory all AFP server connections within the organization

Patch Information

Apple has released security updates addressing this vulnerability. Organizations should apply the following patches as soon as possible:

• macOS Sequoia 15.5: See Apple Security Advisory #122716 for update instructions
• macOS Sonoma 14.7.6: See Apple Security Advisory #122717 for update instructions

Updates can be applied through System Preferences > Software Update on affected macOS systems, or deployed organization-wide using MDM solutions such as Jamf or Mosyle.

Workarounds

• Disable AFP client services if file sharing with AFP servers is not required for business operations
• Implement network-level controls to block AFP connections (TCP port 548) to external or untrusted destinations
• Use alternative file sharing protocols such as SMB or SFTP where possible until patching is complete
• Deploy application whitelisting to prevent users from connecting to unauthorized AFP servers

# Block outbound AFP connections at the macOS firewall level
# Add to /etc/pf.conf or configure via MDM
# Block AFP traffic to non-trusted destinations
sudo pfctl -e
echo "block out proto tcp from any to any port 548" | sudo pfctl -f -