CVE-2023-53751: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53751 is a use-after-free vulnerability in the Linux kernel's CIFS (Common Internet File System) subsystem, specifically affecting the TCP_Server_Info::hostname field. The hostname field can be updated one or more times during a reconnect operation, and insufficient protection of its access outside the reconnect path creates conditions for use-after-free memory corruption. The vulnerability was published on December 8, 2025, and affects Linux kernel versions from the initial commit up to fixed releases including 6.1.28, 6.2.15, 6.3.2, and 6.4. Feedly estimates the severity as HIGH, with an EPSS score of 0.000250 (Feedly, ENISA EUVD).

The root cause is a race condition (CWE-416: Use After Free) in the Linux kernel CIFS client driver. The TCP_Server_Info::hostname pointer can be freed and reallocated during a server reconnect event, but code paths outside the reconnect logic access this pointer without adequate synchronization or locking, leaving a window where a dangling pointer may be dereferenced. An attacker or a concurrent kernel thread triggering reconnect activity could cause the freed memory to be accessed, potentially leading to memory corruption. Fixes were applied across multiple stable kernel branches via commits 64d62ac6d651, c511954bf142, 0b08c4c49920, and 90c49fce1c43 (Kernel Git, ENISA EUVD).

Successful exploitation of this use-after-free vulnerability could result in kernel memory corruption, potentially enabling privilege escalation from a local user to root, system crashes (denial of service), or arbitrary code execution in kernel context. The vulnerability is confined to systems using the CIFS/SMB client subsystem, meaning only hosts actively mounting SMB/CIFS network shares are at risk. Data confidentiality and integrity could be compromised if an attacker leverages kernel-level access to read or modify sensitive memory (Feedly, ENISA EUVD).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2023-53751. The EPSS score is very low at 0.000250, indicating a low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Detection coverage exists via Nessus and Qualys scanners (Feedly).

The Linux kernel maintainers have released patches across multiple stable branches. Users should upgrade to kernel versions 6.1.28, 6.2.15, 6.3.2, or 6.4 (or later) to remediate this vulnerability. Red Hat has issued advisories (RHSA-2026:1512, RHSA-2026:1886, RHSA-2026:1946, RHSA-2026:2490, RHSA-2026:2535, RHSA-2026:2577) addressing this CVE for affected RHEL products. As a temporary workaround where patching is not immediately possible, administrators can avoid mounting CIFS/SMB shares or restrict CIFS module loading on sensitive systems (Red Hat RHSA-2026:1512, Red Hat RHSA-2026:2577).