Cloudanix VulnDB

CVE-2026-68312

None

CVSS

—

EPSS

0.2%

Published

Aug 10, 2026

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A bug in the Linux kernel's handling of network file shares can slowly leak memory when the system is already low on memory, eventually affecting stability.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Low
Impact
Denial Of Service
Component
OS kernel
Class
Other
Remediation
Patch
Effort
Medium
Patch risk
Low

What it actually does

Memory leak of cifsFileInfo structures and associated open server handles when kmalloc fails after canceling deferred close delayed work in cifs_close_deferred_file and related functions under memory pressure.

Why it matters to the business

Gradual kernel memory exhaustion on Linux systems using CIFS/SMB network mounts when subjected to sustained memory pressure, potentially degrading performance or causing instability over time.

How an attack unfolds

An attacker triggers repeated CIFS deferred close operations on a target system while inducing memory pressure to force kmalloc failures after work cancellation, leaving references un-released and accumulating leaks.

How to fix it

Apply the upstream Linux kernel patch that saves the failed-allocation cfile reference, releases the lock, and explicitly calls _cifsFileInfo_put before breaking the loop in the affected deferred-close drain functions.

How to confirm the fix worked

Inspect kernel source or git history for the commit resolving the cifsFileInfo leak on kmalloc failure in cifs_close_deferred_file and sibling functions; verify the fix logic is present in the running kernel build.

Typical attack path

  1. Establish CIFS mounts and generate file open/close activity to populate deferred close queues
  2. Induce memory pressure on the target kernel
  3. Cancel delayed work items via close paths
  4. Force kmalloc failure in list population logic
  5. Repeat to accumulate leaked cifsFileInfo objects and handles

How to detect it

Review kernel logs and slab allocator statistics for repeated allocation failures near CIFS close paths; correlate with increasing cifsFileInfo object counts via kmemleak or similar tools if enabled.

What your security team should do

  • Prioritize kernel updates containing the CIFS deferred-close leak fix when they become available in distribution repositories
  • Monitor memory usage on CIFS-heavy workloads under load to detect anomalous growth
  • Review CIFS mount usage patterns and reduce reliance on deferred close where feasible

The record

In the Linux kernel, the following vulnerability has been resolved: cifs: fix cifsFileInfo leak on kmalloc failure in deferred close drain paths In cifs_close_deferred_file(), cifs_close_all_deferred_files(), and cifs_close_deferred_file_under_dentry(), when a pending deferred close is cancelled via cancel_delayed_work(), the subsequent kmalloc_obj() to add the file to the local processing list may fail under memory pressure. The loop breaks immediately, but the cancelled work is no longer pending (it would have called _cifsFileInfo_put()), and the cfile is never added to file_head for processing. The cifsFileInfo reference and the open server handle both leak. Fix by saving the cfile that failed allocation in a local variable, breaking as before, and calling _cifsFileInfo_put() on it after releasing the lock. Any files later in the iteration are unaffected since their deferred work is still pending and will fire normally.

Affected packages

Ecosystem Package Introduced Fixed