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CVE-2026-23220 medium CVSS 5.5

Vulnerability in Linux kernel (CVE-2026-23220)

Summary

Vulnerability in Linux kernel (CVE-2026-23220). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

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.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-23220 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-23220" on the vendor's site.

CVE-2026-23220 (Linux kernel) — CWE-835 / CVSS v3 5.5
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-835) exists in Linux kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel.

🔥 Severity

Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Linux Kernel
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.164"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.125"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.6.0"},{"fixed":"6.12.72"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.18.11"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.19.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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