Bug 2541286 (CVE-2026-97565)

Summary: CVE-2026-97565 kernel: smb: client: reject short READ responses in CIFSSMBRead()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's SMB (Server Message Block) client. When communicating with a malicious or compromised server, the client fails to verify that an incoming read response meets the expected minimum header size before accessing header fields. A malicious server can send a truncated response packet, triggering an out-of-bounds memory read during header parsing. This flaw primarily leads to a system crash, resulting in a Denial of Service (DoS), or potential information disclosure.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-25 11:15:05 UTC 
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.
Comment 1 gkamathe 2026-09-29 03:35:48 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97565.mbox