CVE-2025-39917
📋 TL;DR
This CVE describes an out-of-bounds write vulnerability in the Linux kernel's BPF crypto subsystem. It allows root-privileged users to write beyond allocated memory boundaries when using the bpf_crypto_crypt function, potentially leading to kernel memory corruption. Only systems with root-privileged BPF programs 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 →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, system crash, or potential privilege escalation if combined with other vulnerabilities to achieve arbitrary code execution in kernel space.
Likely Case
Kernel crash or system instability when malicious root-privileged BPF programs exploit this vulnerability.
If Mitigated
No impact if proper privilege separation prevents unauthorized root access or if BPF crypto functionality is disabled.
🎯 Exploit Status
Exploitation requires root access to load BPF programs. No public exploit code known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with fixes from the referenced commits
Vendor Advisory: https://git.kernel.org/stable/c/0126358df12d6f476f79251d9c398ac5c1b3062d
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fixes. 2. Check distribution-specific security advisories. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable BPF crypto functionality
linuxPrevent loading of BPF programs that use crypto functions
sysctl -w kernel.unprivileged_bpf_disabled=1
echo 1 > /proc/sys/kernel/unprivileged_bpf_disabled
Restrict BPF program loading
linuxLimit BPF program loading to trusted users only
chmod 750 /sys/fs/bpf
setfacl -m u:root:rwx /sys/fs/bpf
🧯 If You Can't Patch
- Implement strict root access controls and monitoring
- Disable BPF subsystem if not required (kernel boot parameter: noprobe=bpf)
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if BPF crypto is enabled: grep -i bpf /proc/config.gz 2>/dev/null || zcat /proc/config.gz 2>/dev/null | grep -i bpfCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated and check for presence of the fix commits: uname -r📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- System crash/panic logs
- BPF program loading failures
Network Indicators:
- None - local exploitation only
SIEM Query:
source="kernel" AND ("Oops" OR "panic" OR "BPF")