CVE-2026-97565
Received Received - Intake

Buffer Overflow in Linux Kernel SMB Client

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: reject short READ responses in CIFSSMBRead() CIFSSMBRead() reads DataLengthHigh, DataLength and DataOffset out of the READ_RSP returned by the server without first checking that a whole READ_RSP was actually received. The length of the response is recorded in rsp_iov.iov_len, but nothing constrains it to be at least read_rsp_size before those fields are dereferenced. A malicious or compromised SMB1 server can return a response shorter than the READ_RSP header, so that parsing the header itself reads past the end of the receive buffer. SMB1 is not negotiated by default; reaching this code requires an explicit vers=1.0 mount. Reject the response unless it is at least read_rsp_size bytes long.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
CVE-2026-97565
EUVD
EUVD-2026-86873

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves the CIFSSMBRead() function which reads response data without verifying the full response length. A malicious SMB1 server could send a response shorter than required, causing the function to read past the end of the receive buffer. This is only exploitable if the system explicitly mounts with vers=1.0.

Detection Guidance

This vulnerability can be detected by checking if SMB1 is enabled on your system. Use the command 'mount | grep vers=1.0' to identify any SMB1 mounts. Additionally, inspect kernel logs for errors related to smb or CIFSSMBRead() parsing failures.

Impact Analysis

If exploited, this vulnerability could allow an attacker to cause a buffer overflow, potentially leading to system crashes, data corruption, or arbitrary code execution on the affected system. However, exploitation requires a vulnerable mount configuration.

Mitigation Strategies

Immediately disable SMB1 by remounting shares with vers=2.0 or higher. Update the Linux kernel to a patched version. Monitor network traffic for unusual SMB1 activity and block SMB1 at the firewall level if possible.

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