CVE-2026-31609
Description
A flaw was found in the Linux kernel's Server Message Block (SMB) client. This vulnerability, a double-free, occurs in the smbd_free_send_io() function after smbd_send_batch_flush() has already freed the memory. This memory corruption can lead to a denial of service (DoS) for the affected system.
Statement
SMB Direct batch flush could double-free send I/O structures; upstream orders frees correctly. Red Hat recommends patched kernels for SMB client users leveraging RDMA/Direct. Unload cifs where SMB client access is not needed.
Mitigation
To mitigate this issue, prevent the cifs module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.
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 | 9.8 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| 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:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability,Integrity
Technical Impact: DoS: Crash, Exit, or Restart
Frequently Asked Questions
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