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.

ubuntu_linux USN-8959-1: Ubuntu 24.04 LTS / Ubuntu 26.04 LTS / Ubuntu Pro Realtime 24.04 LTS : Linux kernel vulnerabilities (USN-8959-1)

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-98400)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
375113	Photon OS 5.0: Linux PHSA-2026-5.0-91-1014	Nessus	PhotonOS Local Security Checks	Local	high
375014	Photon OS 5.0: Linux PHSA-2026-5.0-92-1014	Nessus	PhotonOS Local Security Checks	Local	high
365914	Linux Distros Unpatched Vulnerability : CVE-2026-98400	Nessus	Misc.	Local	medium

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