Linux Kernel up to 6.6.124/6.12.71/6.18.10/6.19.0 ksmbd next_smb2_rcv_hdr_off infinite loop

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.6.124/6.12.71/6.18.10/6.19.0. This issue affects the function next_smb2_rcv_hdr_off of the component ksmbd. This manipulation causes infinite loop. This vulnerability is tracked as CVE-2026-23220. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.6.124/6.12.71/6.18.10/6.19.0. Affected by this vulnerability is the function next_smb2_rcv_hdr_off of the component ksmbd. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-23220 since 01/13/2026. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 299454 (Linux Distros Unpatched Vulnerability : CVE-2026-23220), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.125, 6.12.72, 6.18.11 or 6.19.1 eliminates this vulnerability. Applying the patch 5accdc5b7f28a81bbc5880ac0b8886e60c86e8c8/f7b1c2f5642bbd60b1beef1f3298cbac81eb232c/71b5e7c528315ca360a1825a4ad2f8ae48c5dc16/9135e791ec2709bcf0cda0335535c74762489498 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (299454), EUVD (EUVD-2026-7681) and CERT Bund (WID-SEC-2026-0462). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Open Source Linux Kernel

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 299454
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23220

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.125/6.12.72/6.18.11/6.19.1
Patch: 5accdc5b7f28a81bbc5880ac0b8886e60c86e8c8/f7b1c2f5642bbd60b1beef1f3298cbac81eb232c/71b5e7c528315ca360a1825a4ad2f8ae48c5dc16/9135e791ec2709bcf0cda0335535c74762489498

Timelineinfo

01/13/2026 CVE reserved
02/18/2026 +36 days Advisory disclosed
02/18/2026 +0 days VulDB entry created
05/24/2026 +95 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23220 (🔒)
GCVE (CVE): GCVE-0-2026-23220
GCVE (VulDB): GCVE-100-346537
EUVD: 🔒
CERT Bund: WID-SEC-2026-0462 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 02/18/2026 16:59
Updated: 05/24/2026 22:12
Changes: 02/18/2026 16:59 (59), 02/19/2026 12:43 (2), 02/20/2026 03:07 (7), 02/23/2026 05:46 (1), 03/19/2026 09:01 (10), 05/24/2026 22:12 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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