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CVE-2026-98403 json

s390/boot: Avoid IPL parameter append past command line

published 28d ago modified 23d ago also EUVD-2026-101052

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

s390/boot: Avoid IPL parameter append past command line

A command line may occupy all but the terminating byte of COMMAND_LINE_SIZE. In that case append_ipl_block_parm() passes a zero size to the IPL parameter conversion helpers and points the destination one byte past early_command_line. The helpers subtract one from the unsigned size and write the converted parameter outside the command line buffer.

Convert the IPL parameter in the command line parsing buffer first. A parameter beginning with '=' can then replace the existing command line regardless of its length, while other parameters are appended only when space remains.

Patch / fix

  • Linux Linux 7.3
  • linux Debian 13 6.12.113-1
  • linux Debian 14 7.2.7-1
  • linux-6.12 Debian 12 6.12.113-1~deb12u1

debian advisories DEBIAN-CVE-2026-98403

  • linux Ubuntu 26.04 LTS 7.0.0-42.42
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1016.17
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1016.18
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-42.42.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1015.16
  • linux-hwe-7.0 Ubuntu 24.04 LTS 7.0.0-42.42~24.04.1
  • linux-oem-7.0 Ubuntu 26.04 LTS 7.0.0-1017.17

ubuntu advisories UBUNTU-CVE-2026-98403

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel AlmaLinux 9 5.14.0-687.66.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.66.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.66.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.66.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.66.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.66.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.66.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.66.1.el9_8

almalinux advisories ALSA-2026:95370

  • kernel Rocky Linux 9 5.14.0-687.66.1.el9_8

rocky linux advisories RLSA-2026:95370

Is CVE-2026-98403 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-98403 updated cvss 6.0

kernel: s390/boot: Avoid IPL parameter append past command line

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.66.1.el9_8, perf 5.14.0-687.66.1.el9_8, rtla 5.14.0-687.66.1.el9_8, python3-perf 5.14.0-687.66.1.el9_8, kernel-devel-matched 5.14.0-687.66.1.el9_8, kernel-64k-devel-matched 5.14.0-687.66.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:95370
  • Red Hat Enterprise Linux AppStream EUS (v.10.2) rv 6.12.0-211.75.1.el10_2, perf 6.12.0-211.75.1.el10_2, rtla 6.12.0-211.75.1.el10_2, python3-perf 6.12.0-211.75.1.el10_2, kernel-devel-matched 6.12.0-211.75.1.el10_2, kernel-64k-devel-matched 6.12.0-211.75.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:99139
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.185.1.el8_10, kernel 4.18.0-553.185.1.el8_10, bpftool 4.18.0-553.185.1.el8_10, kernel-core 4.18.0-553.185.1.el8_10, kernel-tools 4.18.0-553.185.1.el8_10, python3-perf 4.18.0-553.185.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:98099
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.66.1.el9_8, kernel-64k 5.14.0-687.66.1.el9_8, kernel-core 5.14.0-687.66.1.el9_8, kernel-tools 5.14.0-687.66.1.el9_8, kernel-modules 5.14.0-687.66.1.el9_8, kernel-64k-core 5.14.0-687.66.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:95370
  • Red Hat Enterprise Linux BaseOS EUS (v.10.2) kernel 6.12.0-211.75.1.el10_2, kernel-64k 6.12.0-211.75.1.el10_2, kernel-core 6.12.0-211.75.1.el10_2, kernel-tools 6.12.0-211.75.1.el10_2, kernel-modules 6.12.0-211.75.1.el10_2, kernel-64k-core 6.12.0-211.75.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:99139
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.66.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.66.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.66.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.66.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.66.1.el9_8
    fixed: vendor fix RHSA-2026:95370
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v.10.2) libperf 6.12.0-211.75.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.75.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.75.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.75.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.75.1.el10_2
    fixed: vendor fix RHSA-2026:99139
show 8 more
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.185.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.185.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.185.1.el8_10
    fixed: vendor fix RHSA-2026:98099
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-kvm 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-core 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-modules 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-debug-kvm 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-debug-core 4.18.0-553.185.1.rt7.526.el8_10, +4 more
    fixed: vendor fix RHSA-2026:98100
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.66.1.el9_8, kernel-rt-64k 5.14.0-687.66.1.el9_8, kernel-rt-core 5.14.0-687.66.1.el9_8, kernel-rt-modules 5.14.0-687.66.1.el9_8, kernel-rt-64k-core 5.14.0-687.66.1.el9_8, kernel-rt-debug-core 5.14.0-687.66.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:95370
  • Red Hat Enterprise Linux Real Time EUS (v.10.2) kernel-rt 6.12.0-211.75.1.el10_2, kernel-rt-64k 6.12.0-211.75.1.el10_2, kernel-rt-core 6.12.0-211.75.1.el10_2, kernel-rt-modules 6.12.0-211.75.1.el10_2, kernel-rt-64k-core 6.12.0-211.75.1.el10_2, kernel-rt-debug-core 6.12.0-211.75.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:99139
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.66.1.el9_8, kernel-rt-core 5.14.0-687.66.1.el9_8, kernel-rt-modules 5.14.0-687.66.1.el9_8, kernel-rt-debug-core 5.14.0-687.66.1.el9_8, kernel-rt-modules-core 5.14.0-687.66.1.el9_8, kernel-rt-debug-modules 5.14.0-687.66.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:95370
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.10.2) kernel-rt 6.12.0-211.75.1.el10_2, kernel-rt-core 6.12.0-211.75.1.el10_2, kernel-rt-modules 6.12.0-211.75.1.el10_2, kernel-rt-debug-core 6.12.0-211.75.1.el10_2, kernel-rt-modules-core 6.12.0-211.75.1.el10_2, kernel-rt-debug-modules 6.12.0-211.75.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:99139
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-core 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-modules 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-debug-core 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-debug-modules 4.18.0-553.185.1.rt7.526.el8_10, kernel-rt-modules-extra 4.18.0-553.185.1.rt7.526.el8_10, +2 more
    fixed: vendor fix RHSA-2026:98100
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-11).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.