CVE-2025-68226
Description
A flaw was found in the Linux kernel’s SMB client implementation (fs/smb/client/cached_dir.c). An earlier commit intended to fix a potential use-after-free in smb2_close_cached_fid() was incompletely backported, resulting in a missing kref_put() call in the cfids_invalidation_worker() function. Under certain conditions, this can lead to a use-after-free of a reference counted object, potentially causing kernel instability or denial of service.
Mitigation
To mitigate this issue, prevent the `cifs` kernel module from loading. This can be achieved by creating a blacklist file.
1. Create a file named `/etc/modprobe.d/blacklist-cifs.conf` with the following content:
blacklist cifs2. Regenerate the initramfs:
install cifs /bin/true
bash3. Reboot the system for the changes to take effect.
dracut -f -v
Note that blacklisting the `cifs` module will disable SMB client functionality, which may impact systems relying on it for network file sharing.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 8.8 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
An adversary that can cause a resource counter to become inaccurate may be able to create situations where resources are not accounted for and not released, thus causing resources to become scarce for future needs.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An adversary that can cause a resource counter to become inaccurate may be able to force an error that causes the product to crash or exit out of its current operation.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
