Linux Kernel up to 7.3-rc1 s390 ipl set_os_info_reipl_block null pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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8.7$0-$5k0.35+

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.6.157/6.12.110/6.18.52/7.2.6/7.3-rc1. This affects the function set_os_info_reipl_block of the component s390 ipl. This manipulation causes null pointer dereference. This vulnerability is registered as CVE-2026-98400. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.6.157/6.12.110/6.18.52/7.2.6/7.3-rc1 and classified as very critical. Affected by this vulnerability is the function set_os_info_reipl_block of the component s390 ipl. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-98400 since 09/25/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation requires an enhanced level of successful authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/14/2026).

Upgrading to version 6.6.158, 6.12.111, 6.18.53, 7.2.7 or 7.3-rc2 eliminates this vulnerability. Applying the patch 030e88812435fc5d6aa42eee41fa77b5ea620327/92d0829eae257544b6b0faccb6e7079c45e22d48/50f9c40768e84f30d374235b3ee3850a94d9ac29/b6bf82bc5e00afaf836f8bb9a676bffc182a6bbd/7f918871112e8e7c581e99eb8e545af4e59c8367 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.1
VulDB Meta Temp Score: 8.7

VulDB Base Score: 9.1
VulDB Temp Score: 8.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.158/6.12.111/6.18.53/7.2.7/7.3-rc2
Patch: 030e88812435fc5d6aa42eee41fa77b5ea620327/92d0829eae257544b6b0faccb6e7079c45e22d48/50f9c40768e84f30d374235b3ee3850a94d9ac29/b6bf82bc5e00afaf836f8bb9a676bffc182a6bbd/7f918871112e8e7c581e99eb8e545af4e59c8367

Timelineinfo

09/25/2026 CVE reserved
10/14/2026 +19 days Advisory disclosed
10/14/2026 +0 days VulDB entry created
10/14/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98400 (🔒)
GCVE (CVE): GCVE-0-2026-98400
GCVE (VulDB): GCVE-100-419845

Entryinfo

Created: 10/14/2026 15:54
Changes: 10/14/2026 15:54 (59)
Complete: 🔍
Cache ID: 216::103

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