CVE-2025-40232: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40232 is a Linux kernel vulnerability in the Runtime Verification (RV) subsystem caused by an inconsistent iterator type cast in enabled_monitors_seq_ops. Specifically, some callbacks treat the iterator as struct rv_monitor * while others treat it as struct list_head *, resulting in a wrong type cast that can crash the system. The vulnerability was published on December 4, 2025, and affects Linux kernel versions from commit de090d1ccae1e191af4beb92964591c6e4f31f28 up to the patched commits in stable branches. Feedly estimates the severity as HIGH, though no official CVSS score has been assigned at this time (Red Hat CVE, EUVD).

The root cause is an improper type cast (CWE-704) within the enabled_monitors_seq_ops callback structure in the Linux kernel's RV (Runtime Verification) subsystem. The iterator used by the seq_ops callbacks was inconsistently typed — some functions assumed struct rv_monitor * while others assumed struct list_head * — leading to memory misinterpretation and a kernel crash. The fix fully converts all callbacks to use struct list_head * as the iterator, making enabled_monitors consistent with available_monitors. The issue was reported by Nathan and resolved via two stable-branch commits: 8948a0338d33c4a7ef1e0c439a3ad1d5fe9355ae and 103541e6a5854b08a25e4caa61e990af1009a52e (Red Hat CVE).

Successful triggering of this vulnerability causes a kernel crash (system panic), resulting in a denial of service on the affected Linux system. Because this is a local kernel-level crash, availability is the primary impact — confidentiality and integrity are not directly affected. Systems with the RV (Runtime Verification) subsystem enabled and accessible are at risk, which is more common in development, debugging, or monitoring-oriented kernel configurations (Red Hat CVE).

There is no known public exploit code or evidence of in-the-wild exploitation for CVE-2025-40232. The EPSS score is very low at 0.000180, indicating a minimal probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation would require local access to a system running a vulnerable kernel with the RV subsystem active (Red Hat CVE).

The vulnerability is fixed in Linux kernel patch commits 8948a0338d33c4a7ef1e0c439a3ad1d5fe9355ae (stable) and 103541e6a5854b08a25e4caa61e990af1009a52e (stable), with patched versions including Linux 6.17.6 and 6.18. Ubuntu has issued security notice USN-7920-1 addressing this vulnerability. Administrators should update to a patched kernel version as soon as possible; as a temporary workaround, disabling the RV (Runtime Verification) subsystem (if not required) can mitigate exposure (Ubuntu USN-7920-1, Red Hat CVE).

Red Hat has acknowledged the vulnerability and published a CVE advisory. Ubuntu issued security notice USN-7920-1 covering this and related kernel vulnerabilities. Coverage has been limited to standard vulnerability tracking and Linux security advisory channels, with no notable researcher commentary or broader media coverage observed (Red Hat CVE, Ubuntu USN-7920-1).