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CVE-2026-98400 low CVSS 5.5

Vulnerability in Linux kernel (CVE-2026-98400)

Summary

Vulnerability in Linux kernel (CVE-2026-98400). 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:

s390/ipl: Fix NULL deref in kdump without re-IPL parm block

Some IPL types, like HMC FTP boot or QEMU direct kernel boot, might
not provide an IPL parameter block. In this case, reipl_type_init()
selects IPL_TYPE_UNKNOWN, and reipl_block_actual remains NULL.

kdump passes the re-IPL parameter block to the dump kernel through
os_info. Before commit 3b9678472bab ("s390/ipl: correct kdump reipl
block checksum calculation"), the os_info entry was added only for
IPL types which initialized reipl_block_actual. That commit moved the
os_info update to machine_crash_shutdown(), making it unconditional. As
a result, set_os_info_reipl_block() dereferences reipl_block_actual for
IPL_TYPE_UNKNOWN. This may happen to work by chance when address zero
contains readable lowcore data and the resulting empty os_info entry is
ignored by the dump kernel.

Skip the os_info update when no re-IPL parameter block is available.
Kdump then collect the dump and reboot without setting re-IPL parameter
block.

Source: GitHub Security Advisories (Global) 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-2026-98400 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-2026-98400" on the vendor's site.

CVE-2026-98400 (Linux kernel) — CWE-476 / 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-476) exists in Linux kernel.

📍 Affected scope

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

🔥 Severity

Severity: Low (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":"4.17.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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