Listen to this Post
How the mentioned CVE works
CVE-2025-37958 is a race condition vulnerability in the Linux kernel’s memory management subsystem, specifically in the handling of Transparent Huge Pages (THP). The flaw occurs during the migration of a THP, a process where a large memory page is moved. Concurrently, a deferred split scan—a background operation that breaks down huge pages—can access the Page Middle Directory (PMD) migration entry associated with the moving page. The code path `split_huge_pmd_locked` lacked a proper early check to validate this PMD entry. Consequently, it could attempt to dereference an invalid, locked migration entry as if it were a valid page frame, leading to a NULL pointer dereference (CWE-476). This invalid memory access triggers a kernel page fault, resulting in a system crash or denial of service, as evidenced by the kernel oops trace featuring BUG: unable to handle page fault for address. The issue was discovered by the syzkaller kernel fuzzer.
dailycve form
Platform: Linux Kernel
Version: Multiple versions
Vulnerability: NULL Pointer Dereference
Severity: Medium
Date: 2025-05-20
Prediction: 2025-07-31
What Undercode Say:
Analytics
Bash commands and codes related to the blog
Check kernel version
uname -r
Check if THP is enabled
cat /sys/kernel/mm/transparent_hugepage/enabled
Update kernel on Amazon Linux 2
sudo yum update kernel –advisory ALAS2KERNEL-5.4-2025-104
Update kernel on RHEL 9.0 SAP
sudo yum update kernel-rt
How Exploit:
A local attacker with basic user privileges could potentially trigger this race condition by manipulating memory operations to coincide with THP migration and deferred split scans. Successful exploitation causes a kernel crash (Denial of Service). There is no evidence of privilege escalation or data compromise.
Protection from this CVE
Apply kernel updates from your Linux distribution vendor. For Red Hat Enterprise Linux 9.0 SAP, update to `kernel-rt-5.14.0-70.140.1.rt21.212.el9_0` or later. For Amazon Linux 2 (Kernel-5.4 Extra), update to `kernel-5.4.295-216.421.amzn2` or later. As a temporary mitigation, consider disabling Transparent Huge Pages, though this may affect performance.
Impact:
The primary impact is system instability and a complete denial of service (DoS) due to a kernel crash. This disrupts the availability of services running on the affected system. The confidentiality and integrity of data are not directly impacted.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
