CVE-2025-21789
📋 TL;DR
This CVE describes an out-of-bounds read vulnerability in the Linux kernel's LoongArch checksum optimization code when processing negative length values. Attackers could potentially read kernel memory, leading to information disclosure or system crashes. Systems running Linux kernels with LoongArch architecture support 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 →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 compromise through information leakage
Likely Case
Kernel panic or system crash causing denial of service
If Mitigated
Limited impact with proper kernel hardening and memory protection mechanisms
🎯 Exploit Status
Requires local access and ability to trigger specific kernel operations with negative length parameters
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with fixes from provided git commits
Vendor Advisory: https://git.kernel.org/stable/c/6287f1a8c16138c2ec750953e35039634018c84a
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version 2. Reboot system 3. Verify kernel version after reboot
🔧 Temporary Workarounds
Disable LoongArch-specific optimizations
LoongArch Linux systemsDisable the specific checksum optimization feature that contains the vulnerability
echo 0 > /sys/kernel/debug/loongarch/csum_optimization
🧯 If You Can't Patch
- Restrict local user access to systems
- Implement strict process isolation and containerization
🔍 How to Verify
Check if Vulnerable:
Check kernel version and architecture: uname -r && uname -mCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and check for presence of fix commits📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Out of bounds memory access warnings in dmesg
Network Indicators:
- None - local vulnerability only
SIEM Query:
search 'kernel panic' OR 'out of bounds' OR 'OoB' in system logs