CVE-2026-53219
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
In the Linux kernel netfilter/x_tables subsystem, a vulnerability allows leaking percpu counter pointers. During rule copy to userspace, a page fault may leave the raw percpu pointer in the user buffer before the sanitized counter is written.
Risk Assessment
The organization risks kernel memory address disclosure, which can aid ASLR bypass or local privilege escalation attacks. Systems with SMP (multi-core) processors are affected.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit in the netfilter branch). For production systems, apply the security patch after testing.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: x_tables: avoid leaking percpu counter pointers The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot. On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by x_tables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace. Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer.