CVE-2025-38312
📋 TL;DR
A division-by-zero vulnerability in the Linux kernel's framebuffer console virtual terminal (fbcvt) subsystem can cause kernel crashes when processing specially crafted display modes. This affects Linux systems with framebuffer console support enabled, potentially leading to denial of service. The vulnerability requires local access or ability to influence display mode parameters.
💻 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 →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 and denial of service, requiring physical or remote console access to recover.
Likely Case
Local denial of service through kernel crash when malicious display mode parameters are processed.
If Mitigated
No impact if patched or if framebuffer console is disabled.
🎯 Exploit Status
Requires local access to trigger the vulnerable code path. The specific conditions (mode->refresh = 0x80000000) are unusual but could be forced.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing the fix commits (2d63433e8eaa3c91b2948190e395bc67009db0d9 and related)
Vendor Advisory: https://git.kernel.org/stable/c/2d63433e8eaa3c91b2948190e395bc67009db0d9
Restart Required: Yes
Instructions:
1. Update kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable framebuffer console
linuxRemove framebuffer console support from kernel configuration
Remove CONFIG_FB_CVT=y from kernel config and rebuild
Or boot with 'nomodeset' kernel parameter
🧯 If You Can't Patch
- Restrict local user access to systems with vulnerable kernels
- Monitor for kernel panic events and investigate root causes
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if framebuffer console is enabled: 'uname -r' and check /boot/config-$(uname -r) for CONFIG_FB_CVTCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and check that the fix commit is present in kernel source📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- Division by zero errors in kernel logs
Network Indicators:
- None - local vulnerability
SIEM Query:
Search for 'kernel panic' or 'division by zero' in system logs🔗 References
- https://git.kernel.org/stable/c/2d63433e8eaa3c91b2948190e395bc67009db0d9
- https://git.kernel.org/stable/c/3f6dae09fc8c306eb70fdfef70726e1f154e173a
- https://git.kernel.org/stable/c/53784073cbad18f75583fd3da9ffdfc4d1f05405
- https://git.kernel.org/stable/c/54947530663edcbaaee1314c01fdd8c72861b124
- https://git.kernel.org/stable/c/610f247f2772e4f92b63442125a1b7ade79898d8
- https://git.kernel.org/stable/c/9027ce4c037b566b658b8939a76326b7125e3627
- https://git.kernel.org/stable/c/ab91647acdf43b984824776559a452212eaeb21a
- https://git.kernel.org/stable/c/b235393b9f43ff86a38ca2bde6372312ea215dc5
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
