CVE-2025-21724
📋 TL;DR
This CVE-2025-21724 is a shift-out-of-bounds vulnerability in the Linux kernel's iommufd/iova_bitmap component. It could allow local attackers to cause undefined behavior, potentially leading to kernel crashes or privilege escalation. Systems running vulnerable Linux kernel versions with IOMMU functionality enabled 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 →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 panic leading to system crash or local privilege escalation to root
Likely Case
Kernel crash causing system instability or denial of service
If Mitigated
No impact if kernel is patched or IOMMU functionality is disabled
🎯 Exploit Status
Requires local access and knowledge of IOMMU operations
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 38ac76fc06bc6826a3e4b12a98efbe98432380a9, 44d9c94b7a3f29a3e07c4753603a35e9b28842a3, b1f8453b8ff1ab79a03820ef608256c499769cb6, d5d33f01b86af44b23eea61ee309e4ef22c0cdfe, e24c1551059268b37f6f40639883eafb281b8b9c
Vendor Advisory: https://git.kernel.org/stable/c/38ac76fc06bc6826a3e4b12a98efbe98432380a9
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Disable IOMMU functionality
allDisable IOMMU in kernel boot parameters to prevent exploitation
Add 'iommu=off' to kernel boot parameters in GRUB configuration
🧯 If You Can't Patch
- Restrict local user access to systems with IOMMU enabled
- Implement strict privilege separation and limit user capabilities
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if it contains the vulnerable iova_bitmap code by examining kernel source or distribution security advisoriesCheck Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched versions from git commits📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- UBSAN shift-out-of-bounds warnings in dmesg
- System crash reports
Network Indicators:
- None - local exploit only
SIEM Query:
Search for kernel panic events or UBSAN warnings in system logs🔗 References
- https://git.kernel.org/stable/c/38ac76fc06bc6826a3e4b12a98efbe98432380a9
- https://git.kernel.org/stable/c/44d9c94b7a3f29a3e07c4753603a35e9b28842a3
- https://git.kernel.org/stable/c/b1f8453b8ff1ab79a03820ef608256c499769cb6
- https://git.kernel.org/stable/c/d5d33f01b86af44b23eea61ee309e4ef22c0cdfe
- https://git.kernel.org/stable/c/e24c1551059268b37f6f40639883eafb281b8b9c
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
