Bug 2546433 (CVE-2026-98168)

Summary: CVE-2026-98168 kernel: smb: client: fix reparse buffer bounds in cifs_query_reparse_point()
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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Doc Text:
A flaw was found in the Linux kernel's Server Message Block (SMB) client. In the reparse point query handling logic, the client fails to properly validate response buffer boundaries before accessing data structures. A malicious or compromised SMB server can exploit this by returning a crafted response with an invalid data offset, triggering an out-of-bounds memory read. This issue can lead to a system crash, resulting in a Denial of Service (DoS), or potentially expose sensitive memory contents.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-06 09:20:14 UTC 
In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix reparse buffer bounds in cifs_query_reparse_point()

In cifs_query_reparse_point(), the start >= end check before casting to
struct reparse_data_buffer * only ensures the start pointer is within the
response. It fails to verify that there is enough space remaining for the
fixed 8-byte header of the structure.

If a server provides a DataOffset that leaves less than 8 bytes remaining,
the check passes, but subsequent reads of ReparseTag and ReparseDataLength
will occur out-of-bounds.

Fix this by ensuring the remaining space is at least the size of the
reparse_data_buffer structure before accessing its fields.
Comment 1 Mauro Matteo Cascella 2026-10-06 18:47:51 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98168.mbox