In the Linux kernel, the following vulnerability has been resolved:
ksmbd: prevent path traversal bypass by restricting caseless retry
ksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path
resolution within the share root. When a crafted path attempts to
escape the share boundary using parent-directory components ('..'),
vfs_path_parent_lookup() detects this and immediately fails,
returning -EXDEV.
However, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.
The function fails to intercept the -EXDEV error and erroneously
falls through to the caseless retry logic, which is intended only
for genuinely missing files. During this retry process, the path
is reconstructed, leading to an unintended LOOKUP_BENEATH bypass
that allows write-capable users to create zero-length files or
directories outside the exported share.
Fix this by ensuring that the execution only proceeds to the caseless
lookup retry when the error is specifically -ENOENT. Any other errors,
such as -EXDEV from a path traversal attempt, must be returned immediately.
ksmbd: prevent path traversal bypass by restricting caseless retry
ksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path
resolution within the share root. When a crafted path attempts to
escape the share boundary using parent-directory components ('..'),
vfs_path_parent_lookup() detects this and immediately fails,
returning -EXDEV.
However, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.
The function fails to intercept the -EXDEV error and erroneously
falls through to the caseless retry logic, which is intended only
for genuinely missing files. During this retry process, the path
is reconstructed, leading to an unintended LOOKUP_BENEATH bypass
that allows write-capable users to create zero-length files or
directories outside the exported share.
Fix this by ensuring that the execution only proceeds to the caseless
lookup retry when the error is specifically -ENOENT. Any other errors,
such as -EXDEV from a path traversal attempt, must be returned immediately.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||
| Linux | Linux | affected |
|
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Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 25 Jul 2026 09:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent path traversal bypass by restricting caseless retry ksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path resolution within the share root. When a crafted path attempts to escape the share boundary using parent-directory components ('..'), vfs_path_parent_lookup() detects this and immediately fails, returning -EXDEV. However, a bug exists in __ksmbd_vfs_kern_path() under caseless mode. The function fails to intercept the -EXDEV error and erroneously falls through to the caseless retry logic, which is intended only for genuinely missing files. During this retry process, the path is reconstructed, leading to an unintended LOOKUP_BENEATH bypass that allows write-capable users to create zero-length files or directories outside the exported share. Fix this by ensuring that the execution only proceeds to the caseless lookup retry when the error is specifically -ENOENT. Any other errors, such as -EXDEV from a path traversal attempt, must be returned immediately. | |
| Title | ksmbd: prevent path traversal bypass by restricting caseless retry | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-25T08:50:43.655Z
Reserved: 2026-07-19T15:36:31.785Z
Link: CVE-2026-64400
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.