CVE-2026-64391
Description
A flaw was found in ksmbd, the in-kernel Server Message Block (SMB) daemon. This vulnerability allows a remote attacker to bypass security restrictions by incorrectly handling credentials for Alternate Data Streams (ADS) input/output (I/O) operations. Instead of using the credentials established when the SMB handle was opened, ksmbd uses the current task's credentials. This misconfiguration can lead to a bypass of inode permissions and Linux Security Module (LSM) policies, potentially resulting in privilege escalation and unauthorized access to system resources.
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 | 5.3 | N/A | 9.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability,Access Control
Technical Impact: Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands; Read Application Data; DoS: Crash, Exit, or Restart
An attacker will be able to gain access to any resources that are allowed by the extra privileges. Common results include executing code, disabling services, and reading restricted data. New weaknesses can be exposed because running with extra privileges, such as root or Administrator, can disable the normal security checks being performed by the operating system or surrounding environment. Other pre-existing weaknesses can turn into security vulnerabilities if they occur while operating at raised privileges.
Frequently Asked Questions
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