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.
Affected products
linux: linux kernel
References10
- git.kernel.org/stable/c/3b1ddba19e77ee35241cd27f16dc3e8d14e08db7 Patch
- git.kernel.org/stable/c/8bd07e417b6bda67e317920584e48cb6ee442a8a Patch
- git.kernel.org/stable/c/ba7f71b6161c0943dafc367565e5843d16b7d505 Patch
- git.kernel.org/stable/c/c688f3ed73d31943334ad2139cb02ec49664322a Patch
- git.kernel.org/stable/c/f98b48151cc502ada59d9778f0112d21f2586ca3 Patch
- git.kernel.org/stable/c/5de2665e913a10ad70aaeecf736b97276e83d995
- git.kernel.org/stable/c/f9dc3be8f403c1216df73e57221f44b045e7ee0b
- access.redhat.com/errata/RHSA-2026:21556
- access.redhat.com/errata/RHSA-2026:21706
- access.redhat.com/errata/RHSA-2026:21745
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 53 · as of 15 November 2026
- CWE
- CWE-476CWE-190CWE-787
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