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9.8
CVE-2026-46195: Linux Kernel: Malicious Server Can Overwrite DACL Pointers
CVE-2026-46195
Summary
A malicious server can exploit a vulnerability in the Linux kernel's SMB client to overwrite DACL pointers, potentially leading to data corruption or security breaches. This issue has been resolved in a recent update. Affected users should update their Linux kernel to the latest version to ensure their system remains secure.
Original title
In the Linux kernel, the following vulnerability has been resolved:
smb: client: validate dacloffset before building DACL pointers
parse_sec_desc(), build_sec_desc(), and the chown path in
id_mod...
Original description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: validate dacloffset before building DACL pointers
parse_sec_desc(), build_sec_desc(), and the chown path in
id_mode_to_cifs_acl() all add the server-supplied dacloffset to pntsd
before proving a DACL header fits inside the returned security
descriptor.
On 32-bit builds a malicious server can return dacloffset near
U32_MAX, wrap the derived DACL pointer below end_of_acl, and then slip
past the later pointer-based bounds checks. build_sec_desc() and
id_mode_to_cifs_acl() can then dereference DACL fields from the wrapped
pointer in the chmod/chown rewrite paths.
Validate dacloffset numerically before building any DACL pointer and
reuse the same helper at the three DACL entry points.
smb: client: validate dacloffset before building DACL pointers
parse_sec_desc(), build_sec_desc(), and the chown path in
id_mode_to_cifs_acl() all add the server-supplied dacloffset to pntsd
before proving a DACL header fits inside the returned security
descriptor.
On 32-bit builds a malicious server can return dacloffset near
U32_MAX, wrap the derived DACL pointer below end_of_acl, and then slip
past the later pointer-based bounds checks. build_sec_desc() and
id_mode_to_cifs_acl() can then dereference DACL fields from the wrapped
pointer in the chmod/chown rewrite paths.
Validate dacloffset numerically before building any DACL pointer and
reuse the same helper at the three DACL entry points.
- https://git.kernel.org/stable/c/3b1ddba19e77ee35241cd27f16dc3e8d14e08db7
- https://git.kernel.org/stable/c/8bd07e417b6bda67e317920584e48cb6ee442a8a
- https://git.kernel.org/stable/c/ba7f71b6161c0943dafc367565e5843d16b7d505
- https://git.kernel.org/stable/c/c688f3ed73d31943334ad2139cb02ec49664322a
- https://git.kernel.org/stable/c/f98b48151cc502ada59d9778f0112d21f2586ca3
Published: 28 May 2026 · Updated: 31 May 2026 · First seen: 28 May 2026