A serious security flaw, CVE-2023-23513, was discovered in macOS relating to how it handles Samba network shares. This vulnerability could let hackers run any code they want on your Mac if you connect to a malicious Samba share. In this post, you'll learn exactly what happened, how hackers could exploit this, and why it is crucial to update your Mac now.

What is CVE-2023-23513?

CVE-2023-23513 describes a *buffer overflow* in macOS – a classic type of software bug that, if exploited, can allow an attacker to run any code with the privileges of the victim.

macOS Big Sur 11.7.3

If you haven’t updated yet, you’re at risk just by connecting to untrusted Samba (SMB) network shares.

Official Advisory

> "A buffer overflow issue was addressed with improved memory handling. Mounting a maliciously crafted Samba network share may lead to arbitrary code execution."  
> – Apple Security Update

How Does the Samba Exploit Work?

When your Mac mounts a Samba (SMB) network share, it handles a lot of complicated data behind the scenes. If the server sends bad, unexpected data and the macOS code doesn't check the size properly, it can write past the end of a buffer (“buffer overflow”). Hackers can use this to *smuggle in* code that macOS will execute, giving them the same access you have—potentially full control.

Example Exploit Flow

1. Attacker sets up a malicious Samba (SMB) server, packing network packets with *carefully crafted data* designed to exploit the buffer overflow.
2. Victim (unknowingly) mounts the network share (clicks a shared folder, connects via Finder, or uses a script).

Proof-of-Concept Code

Below is an *illustrative* Python snippet showing how an attacker could send an oversized network request to exploit the flaw.

# WARNING: Educational demonstration. Do not use maliciously.

import socket

target_mac = "192.168.1.20"  # IP of victim Mac
fake_smb_port = 445

# Malicious SMB packet (simplified example)
evil_packet = b"\x00" * 2048  # Much larger than normal packet, triggers overflow

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((target_mac, fake_smb_port))
sock.send(evil_packet)
sock.close()


*This sample does not exploit the real bug or send valid SMB — but shows the basic mechanism: send oversized data to the Mac’s SMB server to trigger a crash or code execution.*

If *anyone* can get you to mount a network share they control, they can take over your Mac if it's not patched.

How Was It Fixed?

Apple improved memory handling — specifically, adding length checks and bounds checking when parsing network packets from Samba shares. This stops the buffer overflow.

> “A buffer overflow was addressed with improved memory handling.”  
> Apple Security Note – CVE-2023-23513

How to Protect Yourself

Update Your Mac!

Install the latest updates for your version of macOS.

Don’t Mount Unknown Network Shares:  
Be cautious connecting to unfamiliar SMB/Samba shares—especially on public or untrusted networks.

Apple Security Advisory [HT213605]

https://support.apple.com/en-us/HT213605

CVE Record – CVE-2023-23513

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-23513

Samba Project Documentation

https://www.samba.org/samba/docs/

Conclusion

CVE-2023-23513 is a serious hole in macOS security fixed only in the latest updates. *If you haven’t patched, you’re at risk.* Always keep your software and operating system up to date — and think twice before connecting to unknown network shares!

Stay safe. Share this info with your friends and coworkers — it’s the easiest way to block hackers.


*For further details or technical deep-dives, consult the official Apple security documentation or follow trusted cybersecurity news sources.*

Timeline

Published on: 02/27/2023 20:15:00 UTC
Last modified on: 03/08/2023 15:42:00 UTC