CVE-2026-99280
Description
A flaw was found in the Linux kernel's ksmbd. Session registration failures and connection cleanups can drop internal session references while the per-session procfs (process information pseudo-filesystem) entry is still accessible. A local user reading these entries during concurrent session teardown can trigger a deadlock or memory corruption, resulting in a Denial of Service (DoS).
Statement
This vulnerability is rated as having Moderate severity for Red Hat because successful exploitation requires local authenticated access and results exclusively in a denial of service without impacting confidentiality or integrity. By default, Red Hat Enterprise Linux utilizes Samba as the supported userspace SMB solution and does not enable the in-kernel ksmbd server. Consequently, systems operating with default configurations are not exposed unless ksmbd has been explicitly loaded and configured.
Mitigation
To mitigate this vulnerability, prevent the ksmbd kernel module from being loaded:
1. Create a configuration file to disable the module:
echo "install ksmbd /bin/true" > /etc/modprobe.d/ksmbd.conf
2. If the module is already loaded, unload it:
modprobe -r ksmbd
Caveat: Disabling this module prevents the system from running the in-kernel SMB server.
Warning: If the module is currently in use, unloading it will disrupt active SMB connections. A system restart may be required if the module cannot be unloaded dynamically.
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 | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Other); DoS: Crash, Exit, or Restart
Each thread of execution will "hang" and prevent tasks from completing. In some cases, CPU consumption may occur if a lock check occurs in a tight loop.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
