CVE-2026-98167
Description
A flaw was found in the Linux kernel's SMB client. When processing compound encrypted Protocol Data Units (PDUs), the client incorrectly validates the length of individual messages within the compound frame. A malicious or compromised SMB server can exploit this flaw by returning truncated sub-PDUs, triggering an out-of-bounds read during response handling. This vulnerability primarily results in a system crash and Denial of Service (DoS), or potentially the disclosure of sensitive kernel memory.
Statement
The SMB client can validate an encrypted compound response against the size of the complete decrypted frame instead of the size of the current sub-PDU. A malicious or compromised SMB server can send a truncated non-last sub-PDU with a crafted NextCommand value so that smb2_check_message accepts it and smb2_get_data_area_len performs an out-of-bounds read. For the CVSS the PR:N value is used because the attacker needs no privileges on the affected client and only needs control of an SMB server used by that client. The issue is network reachable after an SMB session has been established and can cause a client kernel crash or denial of service. The paranoid score also considers limited confidentiality impact from the out-of-bounds read. There is no demonstrated write primitive, so integrity impact and privilege escalation are not included in the score. SMB services are commonly limited to internal or enterprise networks, but a compromised trusted file server can still expose many connected clients.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 6.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | Required | 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:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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