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CVE-2026-97563

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject out-of-bounds DataOffset in CIFSSMBRead() The SMB1 synchronous read helper CIFSSMBRead() validates the serv…

Published Sep 25, 2026EPSS 0.19%

Overview

CVE-2026-97563 is a known-severity vulnerability. It was published on September 25, 2026.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

smb: client: reject out-of-bounds DataOffset in CIFSSMBRead()

The SMB1 synchronous read helper CIFSSMBRead() validates the server's

DataLength against CIFSMaxBufSize and the caller's count, but never

validates DataOffset. The copy source is formed as

&pSMBr->hdr.Protocol + le16_to_cpu(pSMBr->DataOffset)

and memcpy()'d for DataLength bytes with no check that the

[DataOffset, DataOffset + DataLength) range lies within the response

actually received from the server.

A malicious or compromised SMB1 server can return a response carrying

an in-range DataLength and a large DataOffset, driving the source

pointer past the end of the response buffer. The memcpy() then copies

adjacent kernel heap into the caller's read buffer (information

disclosure), or reads unmapped memory and oopses (denial of service).

SMB1 is not negotiated by default; reaching this code requires an

explicit vers=1.0 mount.

Both DataOffset and the re

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Frequently asked questions

What is CVE-2026-97563?

CVE-2026-97563 is a known-severity vulnerability. It was published on September 25, 2026.

How severe is CVE-2026-97563?

CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.

How do I fix or remediate CVE-2026-97563?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-97563?

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