Skip to main content

Linux kernel ksmbd CVE-2026-68083

| EUVDEUVD-2026-55264 CRITICAL
2026-08-10 Linux GHSA-fxqh-hm36-rrq9
Information Disclosure Linux
Critical
Disputed · 9.1 Vendor: Linux
Share

Severity by source

Sources disagree (Medium–Critical)
Vendor (Linux) PRIMARY
9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
vuln.today AI
7.1 HIGH

Description requires an authenticated client (PR:L) and a won TOCTOU race (AC:H); out-of-share create/hardlink gives high integrity/availability and some confidentiality (C:L).

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:H
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
6.3 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:N
Red Hat
MEDIUM
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 14, 2026 - 02:09 vuln.today
CVSS changed
Aug 13, 2026 - 23:37 NVD
9.1 (CRITICAL)
Patch available
Aug 10, 2026 - 13:03 EUVD
CVE Published
Aug 10, 2026 - 11:41 cve.org
CRITICAL 9.1
CVE Published
Aug 10, 2026 - 11:41 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix path resolution in ksmbd_vfs_kern_path_create

The SMB2 open lookup is rooted at the share with LOOKUP_BENEATH, but the create/mkdir/hardlink sink is not: ksmbd_vfs_kern_path_create() builds an absolute path with convert_to_unix_name() and resolves it from AT_FDCWD via start_creating_path(), so a ".." component is walked from the real filesystem root and escapes the export.

An authenticated client races a missing path component so the rooted open lookup returns -ENOENT (taking the create branch) while the same component is present (a directory) when the create walk runs; the create then resolves ".." out of the share.

Root the create walk at the share like the lookup and rename paths already are: resolve the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH, &share_conf->vfs_path) and create the final component with start_creating_noperm(). convert_to_unix_name() then has no callers and is removed.

AnalysisAI

Directory-traversal / share escape in the Linux kernel's in-kernel SMB3 server (ksmbd) lets an authenticated SMB client create files, directories, or hardlinks outside the exported share. The SMB2 open lookup is correctly rooted at the share with LOOKUP_BENEATH, but ksmbd_vfs_kern_path_create() built an absolute path via convert_to_unix_name() and resolved it from AT_FDCWD, so a '..' component walked from the real filesystem root and escaped the export. It is exploited through a TOCTOU race and has no public exploit identified at time of analysis; EPSS is low (0.17%, 6th percentile) and it is not in CISA KEV.

Technical ContextAI

ksmbd is the kernel-space SMB/CIFS file server shipped in mainline Linux (since 5.15), an alternative to userspace Samba for exporting shares over SMB2/3. The root cause is a path-confinement inconsistency: while the open/lookup, rename, and hardlink lookup paths confine resolution to the share root using LOOKUP_BENEATH against share_conf->vfs_path, the create/mkdir sink resolved an absolute Unix path from AT_FDCWD via start_creating_path(), bypassing the beneath-root confinement so a '..' component traverses out of the export. Functionally this is a path-traversal weakness (CWE-22) enabled by a time-of-check/time-of-use race (CWE-362); the input lists CWE as N/A. The fix re-roots the create walk at the share by resolving the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH, &share_conf->vfs_path) and creating the final component with start_creating_noperm(), after which convert_to_unix_name() becomes dead code and is removed. The affected CPE is cpe:2.3:a:linux:linux:*, i.e. the kernel itself, but only builds with the ksmbd server enabled and actively exporting shares are exposed.

RemediationAI

Upgrade to a fixed Linux kernel: 6.12.97 or later on the 6.12 line, 6.18.40 or later, 7.1.5 or later, or mainline 7.2-rc1 (Vendor-released patch confirmed via git.kernel.org stable commits 489d1ded, c7c884a1, 98185b30, 1c895196). If you cannot patch immediately, the most effective compensating control is to stop using the in-kernel ksmbd server - unload/disable the ksmbd module and export shares via userspace Samba instead, which does not use this code path (trade-off: a service migration and possible feature/performance differences). Where ksmbd must remain, restrict SMB access (TCP/445) to trusted authenticated users via firewall and share ACLs, and avoid granting create/write permissions on shares to untrusted accounts, since exploitation requires an authenticated session able to trigger create/mkdir/hardlink operations (trade-off: reduces but does not eliminate risk from authorized users). Track the fix through your distribution's kernel advisory and reboot into the patched kernel.

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5
CVE-2014-6324 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

Share

CVE-2026-68083 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy