CVE-2026-90176
Published: September 19, 2026Last modified: October 6, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: Do not skip lock checks for single-byte ranges check_lock_range() uses inclusive ranges. Its callers pass the end offset as start + length - 1, so start == end represents a valid single-byte range rather than an empty range. The start == end shortcut therefore skips mandatory byte-range lock checks for one-byte reads, writes, copychunk operations and one-byte truncate ranges. A conflicting lock covering that byte is not checked and the operation is allowed to proceed. Remove the shortcut. The truncate size == inode->i_size case is already handled by only calling check_lock_range() when the new size differs from the current file size.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 8.1 |
| Attack Vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | NONE |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Fixed (6.1.189-r0) |
| 25 LTS | linux-lts | Fixed (6.12.111-r0) | |
| Stream | linux-lts | Not affected (6.1.33-r0) |
References
- https://git.kernel.org/stable/c/07a9e289ff7edcc004f58952405f8a65c4e37512
- https://git.kernel.org/stable/c/84c2d8e807ac489f5c91769293fb15dfdae8bae8
- https://git.kernel.org/stable/c/993e0158331d37c04da18efe551b5e1e35fb3078
- https://git.kernel.org/stable/c/a89cc145832e81c32199d4ca2e1ea8bd51ed601d
- https://git.kernel.org/stable/c/d40c24634fe077a0dc91fd11fccf44ce12b454d5
- https://git.kernel.org/stable/c/f751d6e39d4c937c45f8fedc66699aa7d2d52288