Описание
In the Linux kernel, the following vulnerability has been resolved:
cifs: validate DFS referral string offsets
parse_dfs_referrals() validates that the response header and referral
array fit in the received buffer, but each referral also contains string
offsets supplied by the server.
Those offsets are used to compute the DfsPath and NetworkAddress string
pointers without checking whether they still point inside the response
buffer. A malformed referral can therefore make the computed pointer
exceed the end of the buffer. The resulting negative max_len is then
passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it
to kstrndup() as a size_t, allowing strnlen() to read out of bounds.
Validate each string offset before deriving the string pointer.
A flaw was found in the Linux kernel's CIFS component. A remote attacker could exploit this vulnerability by providing a specially crafted Distributed File System (DFS) referral. The system fails to properly validate string offsets within these referrals, which can lead to an out-of-bounds read. This could result in information disclosure or a denial of service.
Меры по смягчению последствий
Prevent the CIFS kernel module from loading if SMB/CIFS network file shares are not required:
- Blacklist the
cifskernel module by creating a modprobe configuration file:
- If the module is currently loaded, unmount all active CIFS mounts and unload the module:
Caveats:
Disabling the cifs module prevents the system from mounting SMB and CIFS network file systems. If active shares cannot be unmounted or the module cannot be unloaded immediately, a system reboot will be required to apply the change.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| 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 8 | kernel-rt | Will not fix | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 10 | kernel | Fixed | RHSA-2026:81406 | 12.10.2026 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2026:82807 | 14.10.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:81552 | 13.10.2026 |
| Red Hat Enterprise Linux 9 | kernel | Fixed | RHSA-2026:81552 | 13.10.2026 |
| Shadow Migration Toolkit for Virtualization for RHEL 10 | kernel | Fixed | RHSA-2026:81406 | 12.10.2026 |
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Дополнительная информация
Статус:
EPSS
8.1 High
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: cifs: validate DFS referral string offsets parse_dfs_referrals() validates that the response header and referral array fit in the received buffer, but each referral also contains string offsets supplied by the server. Those offsets are used to compute the DfsPath and NetworkAddress string pointers without checking whether they still point inside the response buffer. A malformed referral can therefore make the computed pointer exceed the end of the buffer. The resulting negative max_len is then passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it to kstrndup() as a size_t, allowing strnlen() to read out of bounds. Validate each string offset before deriving the string pointer.
In the Linux kernel, the following vulnerability has been resolved: cifs: validate DFS referral string offsets parse_dfs_referrals() validates that the response header and referral array fit in the received buffer, but each referral also contains string offsets supplied by the server. Those offsets are used to compute the DfsPath and NetworkAddress string pointers without checking whether they still point inside the response buffer. A malformed referral can therefore make the computed pointer exceed the end of the buffer. The resulting negative max_len is then passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it to kstrndup() as a size_t, allowing strnlen() to read out of bounds. Validate each string offset before deriving the string pointer.
In the Linux kernel, the following vulnerability has been resolved: c ...
EPSS
8.1 High
CVSS3