CVE-2023-53852: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53852 is a memory leak vulnerability in the Linux kernel's nvme-core subsystem, specifically within the nvme_ctrl_dhchap_secret_store() function. The flaw causes kernel memory allocated via kmalloc to not be freed when a new DH-HMAC-CHAP secret is stored, resulting in a kernel memory leak. It affects the Linux kernel and was published on December 9, 2025. The vulnerability is estimated to be of MEDIUM severity, with an EPSS score of 0.00018 (Feedly, Vulners).

The root cause is a missing kfree() call in nvme_ctrl_dhchap_secret_store() before the function returns, classified as CWE-401 (Missing Release of Memory after Effective Lifetime). When a user writes a new DH-HMAC-CHAP authentication secret to the NVMe controller's sysfs attribute, the function allocates a new buffer via __kmalloc but fails to free the previously allocated dhchap_secret buffer, causing a kernel memory leak. The leak is triggered via the kernfs_fop_write_iter → vfs_write → ksys_write syscall path, as evidenced by the kmemleack backtrace in the vulnerability description. The fix involves freeing the old dhchap_secret before assigning the new value (Feedly, Kernel Git).

The vulnerability results in a kernel memory leak, gradually consuming non-reclaimable kernel memory each time a DH-HMAC-CHAP secret is updated on an NVMe controller. Over time, repeated writes to the affected sysfs attribute can degrade system availability by exhausting kernel memory resources, potentially leading to system instability or denial of service. There is no direct confidentiality or integrity impact, and exploitation requires local access to write to the NVMe controller's sysfs interface (Feedly).

The fix has been committed to the Linux kernel stable tree, adding a kfree() call for the existing dhchap_secret before assigning the new value in nvme_ctrl_dhchap_secret_store(). Patches are referenced in multiple stable kernel commits (Kernel Git, Kernel Git, Kernel Git, Kernel Git). SUSE has also issued advisories incorporating this fix. Administrators should update to a patched kernel version; as a workaround, avoid repeatedly writing new DH-HMAC-CHAP secrets to NVMe controller sysfs attributes on unpatched systems (Linux Security).