Bug 2554892 (CVE-2026-98454) - CVE-2026-98454 kernel: smb: client: fix create context out-of-bounds reads
Summary: CVE-2026-98454 kernel: smb: client: fix create context out-of-bounds reads
Keywords:
Status: NEW
Alias: CVE-2026-98454
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-18 15:26 UTC by OSIDB Bzimport
Modified: 2026-10-19 14:06 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-10-18 15:26:02 UTC
In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix create context out-of-bounds reads

smb2_parse_contexts() validates the complete create-context area but
does not limit each record to its Next field before dispatching it.  A
malformed chain can therefore expose bytes beyond the current context to
a handler.  The QFid handler also used a full response-structure cast
although it only reads DiskFileId.

The SMB2/SMB3 lease parsers made the same layout assumption: they read
LeaseState and LeaseFlags at canonical offsets rather than at
DataOffset.  A valid non-canonical DataOffset could therefore yield
unrelated in-bounds data, while a short DataLength was still accepted.

Limit each context to its Next value, reject offsets before the context
header, and reject malformed chains.  Bound the name range by the current
context and do not dispatch a known handler when DataLength is zero.  Read
the QFid DiskFileId only when the context data covers that field.  Parse the
lease context from DataOffset and require DataLength to match the v1 or v2
lease_context size used by ksmbd.  A size mismatch skips lease parsing
without failing the open.


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