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high 7.8

CVE-2026-99156 json

scsi: st: Fix use-after-free race between st_remove() and st_open()

published 14d ago modified 11d ago also EUVD-2026-111908

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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

scsi: st: Fix use-after-free race between st_remove() and st_open()

st_remove() drops the probe reference on the scsi_tape with kref_put() and only afterwards removes its index from st_index_idr. If that was the last reference, scsi_tape_release() frees the structure while it is still published in the idr.

scsi_tape_get(), called from st_open(), looks up the tape in st_index_idr and takes a reference under st_ref_mutex and st_index_lock. remove_cdevs() does not wait for opens that are already past chrdev_open(), so an open that is blocked on st_ref_mutex while st_remove() holds it can take the mutex as soon as st_remove() drops it, find the freed tpnt in the idr and call kref_get() on it:

BUG: KASAN: slab-use-after-free in st_open Write of size 4 ... st_open (drivers/scsi/st.c:254 drivers/scsi/st.c:1291) chrdev_open ... Freed by task ...: kfree st_remove (drivers/scsi/st.c:4512)

Remove the index from the idr before dropping the reference, all under st_ref_mutex. A concurrent scsi_tape_get() now either runs first and holds a valid reference that keeps the tape alive, or runs afterwards and finds nothing, so st_open() fails with -ENXIO.

This restores the ordering st_remove() had before the conversion to st_index_idr, where the tape was unpublished from scsi_tapes[] before the final kref_put().

Patch / fix

  • Linux Linux 7.3
  • linux Debian 13 6.12.115-2
  • linux Debian 14 7.2.13-1

debian advisories DEBIAN-CVE-2026-99156

  • linux Ubuntu 26.10 7.3.0-10.10
  • linux-aws Ubuntu 26.10 7.3.0-1004.4
  • linux-gcp Ubuntu 26.10 7.3.0-1004.4
  • linux-raspi Ubuntu 26.10 7.3.0-1004.4
  • linux-riscv Ubuntu 26.10 7.3.0-10.10.1
  • linux-oracle Ubuntu 26.10 7.3.0-1004.4
  • linux-realtime Ubuntu 26.10 7.3.0-10.10.1

ubuntu advisories UBUNTU-CVE-2026-99156

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 Azure Linux 3.0 6.6.161.1-1

azure linux advisories AZL-111296

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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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-2026-99156 updated cvss 4.7

kernel: kernel: Denial of Service via use-after-free race condition in SCSI tape driver

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, 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 BaseOS (v. 8) perf 4.18.0-553.186.1.el8_10, kernel 4.18.0-553.186.1.el8_10, bpftool 4.18.0-553.186.1.el8_10, kernel-core 4.18.0-553.186.1.el8_10, kernel-tools 4.18.0-553.186.1.el8_10, python3-perf 4.18.0-553.186.1.el8_10, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.186.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.186.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.186.1.el8_10
    fixed: vendor fix RHSA-2026:99015
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-kvm 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-core 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-modules 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-debug-kvm 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-debug-core 4.18.0-553.186.1.rt7.527.el8_10, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-core 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-modules 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-debug-core 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-debug-modules 4.18.0-553.186.1.rt7.527.el8_10, kernel-rt-modules-extra 4.18.0-553.186.1.rt7.527.el8_10, +2 more
    fixed: vendor fix RHSA-2026:99031

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

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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