CVE-2025-21742
📋 TL;DR
This CVE describes an out-of-bounds read vulnerability in the Linux kernel's usbnet ipheth driver for iOS tethering. Attackers could exploit this to read kernel memory, potentially leading to information disclosure or system crashes. Systems using Linux kernel with iOS USB tethering are affected.
💻 Affected Systems
- Linux kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel memory disclosure leading to privilege escalation or system crash, though full exploitation requires additional conditions beyond this specific vulnerability.
Likely Case
System instability, crashes, or denial of service when using iOS USB tethering with vulnerable kernel versions.
If Mitigated
Minimal impact if patched or iOS tethering is disabled; the vulnerability requires physical USB connection to iOS devices.
🎯 Exploit Status
Exploitation requires physical USB access to iOS device and additional conditions beyond this specific vulnerability; the CVE description notes this commit alone doesn't fully address the OoB read.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 2b619445dcb6dab97d8ed033fb57225aca1288c4, 86586dcb75cb8fd062a518aca8ee667938b91efb, 8fb062178e1ce180e2cfdc9abc83a1b9fea381ca, cf1ac7f7cf601ac31d1580559c002b5e37b733b7
Vendor Advisory: https://git.kernel.org/stable/c/2b619445dcb6dab97d8ed033fb57225aca1288c4
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version 2. Check distribution-specific security advisories 3. Reboot system after kernel update
🔧 Temporary Workarounds
Disable iOS USB tethering
allPrevent use of vulnerable ipheth driver by disabling iOS USB tethering functionality
modprobe -r ipheth
echo 'blacklist ipheth' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Disable iOS USB tethering and remove ipheth kernel module
- Restrict physical USB access to trusted devices only
🔍 How to Verify
Check if Vulnerable:
Check if ipheth module is loaded: lsmod | grep iphethCheck Version:
uname -rVerify Fix Applied:
Check kernel version contains fix commits: uname -r and verify against patched versions📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- System crashes when iOS device connected via USB
Network Indicators:
- Unusual USB device connection patterns
SIEM Query:
source="kernel" AND ("oops" OR "panic") AND "ipheth"