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Linux KernelOperating system · Linux

CVE-2026-23220

MEDIUM · 5.5 CVSS v3.1 Published 2026-02-18
Fix available
A fix is available. Upgrade to 5.16 / 6.1.164 or later.
See remediation →
57/100
Remediation priority · Elevated
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: ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths The problem occurs when a signed request fails smb2 signature verification check. In __process_request(), if check_sign_req() returns an error, set_smb2_rsp_status(work, STATUS_ACCESS_DENIED) is called. set_smb2_rsp_status() set work->next_smb2_rcv_hdr_off as zero. By resetting next_smb2_rcv_hdr_off to zero, the pointer to the next command in the chain is lost. Consequently, is_chained_smb2_message() continues to point to the same request header instead of advancing. If the header's NextCommand field is non-zero, the function returns true, causing __handle_ksmbd_work() to repeatedly process the same failed request in an infinite loop. This results in the kernel log being flooded with "bad smb2 signature" messages and high CPU usage. This patch fixes the issue by changing the return value from SERVER_HANDLER_CONTINUE to SERVER_HANDLER_ABORT. This ensures that the processing loop terminates immediately rather than attempting to continue from an invalidated offset.

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
How this class of weakness works · CWE-835

Crafted input drives a loop whose exit condition is never satisfied, hanging the thread and starving the service of the resource it occupies. A single request can be enough to take a worker down. Remediation is bounding iteration counts and validating the conditions that are supposed to terminate the loop.

General guidance for the infinite loop class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 5.15.145, < 5.16>= 6.1.71, < 6.1.164>= 6.6.1, < 6.6.125>= 6.7, < 6.12.72>= 6.13, < 6.18.11>= 6.19, < 6.19.1= 6.6

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

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 5.16 / 6.1.164 / 6.6.125 or later
Fixed in 5.166.1.1646.6.125
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel 6.12.72 or later (or the latest stable kernel for your respective branch: 5.16+, 6.1.164+, 6.6.125+)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which affected kernel branch your current version belongs to (5.15.x, 6.1.x, 6.6.x, or 6.7-6.12.x)
  3. Update the system package repository to fetch the latest stable kernel packages
  4. Upgrade the Linux kernel to a patched version: For 5.15.x branch, upgrade to 5.16 or later; For 6.1.x branch, upgrade to 6.1.164 or later; For 6.6.x branch, upgrade to 6.6.125 or later; For 6.7-6.12.x branch, upgrade to 6.12.72 or later
  5. Reboot the system to load the new kernel using `sudo reboot`
  6. Verify the new kernel version is running with `uname -r`
  7. Confirm the ksmbd module is loaded if SMB server functionality is needed
Caveat Kernel upgrades may require rebuilding out-of-tree kernel modules; ensure compatibility of third-party drivers before upgrading

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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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-2026-23220 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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