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Linux KernelOperating system · Linux

CVE-2026-46195

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-28
Fix available
A fix is available. Upgrade to 6.6.140 / 6.12.88 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in the Linux kernel's SMB client allows a malicious server to supply a large dacloffset value that, when added to the security descriptor pointer on 32-bit systems, wraps around the allocation boundary. This enables the attacker to bypass pointer-based bounds checks and dereference corrupted memory in the chmod/chown code paths, potentially leading to kernel memory corruption and privilege escalation.

MitigationApply the kernel patch that validates dacloffset numerically before deriving any DACL pointers, and restrict SMB connections to trusted servers to prevent exploitation by malicious servers.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.12, < 6.6.140>= 6.7, < 6.12.88>= 6.13, < 6.18.30>= 6.19, < 7.0.7= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check system architecture
    Run 'uname -m' or 'getconf LONG_BIT' to determine if the system is 32-bit (i386, i686, or LONG_BIT returns 32)
    Affected if The system is 32-bit - this vulnerability specifically requires a 32-bit architecture for the pointer wrap to bypass checks
  2. Check kernel version
    Run 'uname -r' to get the kernel version, then compare against the affected ranges: 5.12 to < 6.6.140, 6.7 to < 6.12.88, 6.13 to < 6.18.30, 6.19 to < 7.0.7, or exactly 7.1
    Affected if The kernel version falls within any of the affected ranges listed
  3. Check if CIFS/SMB client is in use
    Run 'lsmod | grep cifs' to check if the CIFS kernel module is loaded, or check for smbclient binary at /usr/bin/smbclient
    Affected if The CIFS kernel module (cifs.ko) is loaded or smbclient utility is installed and in use
  4. Check for active SMB connections
    Run 'mount | grep cifs' or 'smbstatus' (if available) to list active or mounted SMB/CIFS shares
    Affected if There are active CIFS mounts or SMB connections to remote servers - the flaw is triggered when connecting to a malicious SMB server
  5. Identify SMB server trust status
    Review the list of CIFS mounts or SMB connections and determine whether any connect to untrusted or potentially malicious SMB servers
    Affected if Any CIFS mount connects to an untrusted or unknown SMB server, as the vulnerability is triggered by a malicious server supplying a crafted dacloffset value

A system is affected if it is 32-bit Linux running a kernel version within the affected ranges AND uses the CIFS/SMB client to connect to untrusted SMB servers.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.140 / 6.12.88 / 6.18.30 or later
Fixed in 6.6.1406.12.886.18.30
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch that validates dacloffset numerically before deriving any DACL pointers, and restrict SMB connections to trusted servers to prevent exploitation by malicious servers.

Recommended fix High confidence

Linux kernel 6.6.140 or 6.12.88 or 6.18.30 or 7.0.7 (depending on which major version branch you are on)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which version range your current kernel falls into from the affected versions: >= 5.12, < 6.6.140; >= 6.7, < 6.12.88; >= 6.13, < 6.18.30; or >= 6.19, < 7.0.7
  3. Upgrade the Linux kernel to a fixed release: 6.6.140+ (for kernels 5.12-6.6.x), 6.12.88+ (for kernels 6.7-6.12.x), 6.18.30+ (for kernels 6.13-6.18.x), or 7.0.7+ (for kernels 6.19+)
  4. Update kernel packages using your distribution's package manager (e.g., `apt-get update && apt-get upgrade` for Debian/Ubuntu, `yum update` for RHEL/CentOS, or `dnf upgrade` for Fedora)
  5. Reboot the system to load the new kernel
  6. Verify the new kernel version is running with `uname -r` and confirm it meets the minimum fixed version for your previous branch
Caveat Kernel upgrades may require reboot and could introduce compatibility issues with custom modules or older drivers; test in staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,860
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-46195 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data