Описание
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.
A flaw was found in the Linux kernel's Server Message Block (SMB) client. A malicious server can exploit this vulnerability on 32-bit systems by providing a crafted dacloffset value. This can cause a pointer wrap, leading to the dereferencing of invalid Discretionary Access Control List (DACL) fields during chmod or chown operations. This memory corruption could potentially allow the malicious server to bypass security mechanisms or cause a denial of service.
Отчет
This is an Important flaw in the Linux kernel's Server Message Block (SMB) client, affecting 32-bit Red Hat Enterprise Linux systems. A malicious SMB server could exploit a pointer wrap vulnerability during chmod or chown operations, potentially leading to memory corruption, a denial of service, or security mechanism bypass. Exploitation requires the affected 32-bit system to connect to a specially crafted malicious SMB server.
Меры по смягчению последствий
To mitigate this issue, avoid mounting shares from untrusted SMB servers on 32-bit Red Hat Enterprise Linux systems. If interaction with untrusted SMB servers is unavoidable, consider isolating affected systems or restricting network access to only known, trusted SMB servers.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Affected | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2026:21745 | 28.05.2026 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2026:21706 | 28.05.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:21556 | 28.05.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:21556 | 28.05.2026 |
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Дополнительная информация
Статус:
EPSS
7.5 High
CVSS3
Связанные уязвимости
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.
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
In the Linux kernel, the following vulnerability has been resolved: s ...
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.
EPSS
7.5 High
CVSS3