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Fencer Vulns
high 7.8

CVE-2026-63802 json

blk-cgroup: fix UAF in __blkcg_rstat_flush()

published 2026-07-19 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-45468

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 0%
public exploits
0
none known

Summary

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

blk-cgroup: fix UAF in __blkcg_rstat_flush()

When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries.

Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing.

Patch / fix

  • Linux Linux 6.4, 6.6.144, 6.12.95, 6.18.38, 7.1.3, 7.2
  • linux Debian 13 6.12.95-1
  • linux Debian 14 7.1.3-1

debian advisories DEBIAN-CVE-2026-63802

  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1006.7

ubuntu advisories UBUNTU-CVE-2026-63802

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 RHEL 10.2 6.12.0-211.59.1.el10_2
  • rv RHEL 10.2 6.12.0-211.59.1.el10_2
  • perf RHEL 10.2 6.12.0-211.59.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.59.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.59.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.59.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.59.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.59.1.el10_2

red hat advisories RHSA-2026:84793RHSA-2026:79783RHSA-2026:71233RHSA-2026:71232RHSA-2026:67469RHSA-2026:67468

  • kernel-livepatch-SLE16_Update_5 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 12-160000.1.1
  • kernel-livepatch-SLE16_Update_9 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 8-160000.1.1
  • kernel-livepatch-SLE16_Update_0 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 19-160000.4.3
  • kernel-livepatch-MICRO-6-0-RT_Update_18 Linux Micro 6.1, Linux Micro 6.0 11-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_15 Linux Micro 6.1, Linux Micro 6.0 12-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_14 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_13 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0-RT_Update_12 Linux Micro 6.1, Linux Micro 6.0 17-1.1

suse advisories SUSE-SU-2026:24107-1SUSE-SU-2026:24108-1SUSE-SU-2026:24174-1SUSE-SU-2026:24175-1SUSE-SU-2026:24106-1SUSE-SU-2026:24173-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1openSUSE-SU-2026:11339-1

  • kernel AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-64k-core AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-debug-core AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-64k-modules AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-debug-modules AlmaLinux 9 5.14.0-687.51.1.el9_8
  • kernel-64k-debug-core AlmaLinux 9 5.14.0-687.51.1.el9_8

almalinux advisories ALSA-2026:71232ALSA-2026:71233ALSA-2026:67468ALSA-2026:67469

  • kernel Rocky Linux 9 5.14.0-687.51.1.el9_8
  • kernel-rt Rocky Linux 8 4.18.0-553.163.1.rt7.504.el8_10
  • kernel Rocky Linux 8 4.18.0-553.163.1.el8_10

rocky linux advisories RLSA-2026:71232RLSA-2026:67469RLSA-2026:67468

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-2026-63802 updated cvss 7.0

kernel: blk-cgroup: fix UAF in __blkcg_rstat_flush()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: no fix planned “Out of support scope”
  • 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
    affected: no fix available
  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.152.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.152.1.el9_6
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.51.1.el9_8, perf 5.14.0-687.51.1.el9_8, rtla 5.14.0-687.51.1.el9_8, python3-perf 5.14.0-687.51.1.el9_8, kernel-devel-matched 5.14.0-687.51.1.el9_8, kernel-64k-devel-matched 5.14.0-687.51.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:71232
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.59.1.el10_2, perf 6.12.0-211.59.1.el10_2, rtla 6.12.0-211.59.1.el10_2, python3-perf 6.12.0-211.59.1.el10_2, kernel-devel-matched 6.12.0-211.59.1.el10_2, kernel-64k-devel-matched 6.12.0-211.59.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:71233
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) perf 5.14.0-284.200.1.el9_2, rtla 5.14.0-284.200.1.el9_2, kernel-devel-matched 5.14.0-284.200.1.el9_2, kernel-64k-devel-matched 5.14.0-284.200.1.el9_2, kernel-debug-devel-matched 5.14.0-284.200.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.200.1.el9_2, +5 more
    fixed: vendor fix RHSA-2026:92993
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.158.1.el9_4, perf 5.14.0-427.158.1.el9_4, rtla 5.14.0-427.158.1.el9_4, kernel-devel-matched 5.14.0-427.158.1.el9_4, kernel-64k-devel-matched 5.14.0-427.158.1.el9_4, kernel-debug-devel-matched 5.14.0-427.158.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:91489
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.152.1.el9_6, perf 5.14.0-570.152.1.el9_6, rtla 5.14.0-570.152.1.el9_6, python3-perf 5.14.0-570.152.1.el9_6, kernel-devel-matched 5.14.0-570.152.1.el9_6, kernel-64k-devel-matched 5.14.0-570.152.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:91492
show 26 more
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.163.1.el8_10, kernel 4.18.0-553.163.1.el8_10, bpftool 4.18.0-553.163.1.el8_10, kernel-core 4.18.0-553.163.1.el8_10, kernel-tools 4.18.0-553.163.1.el8_10, python3-perf 4.18.0-553.163.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:67468
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.51.1.el9_8, kernel-64k 5.14.0-687.51.1.el9_8, kernel-core 5.14.0-687.51.1.el9_8, kernel-tools 5.14.0-687.51.1.el9_8, kernel-modules 5.14.0-687.51.1.el9_8, kernel-64k-core 5.14.0-687.51.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:71232
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.59.1.el10_2, kernel-64k 6.12.0-211.59.1.el10_2, kernel-core 6.12.0-211.59.1.el10_2, kernel-tools 6.12.0-211.59.1.el10_2, kernel-modules 6.12.0-211.59.1.el10_2, kernel-64k-core 6.12.0-211.59.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:71233
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.221.1.el8_6, kernel 4.18.0-372.221.1.el8_6, bpftool 4.18.0-372.221.1.el8_6, kernel-core 4.18.0-372.221.1.el8_6, kernel-tools 4.18.0-372.221.1.el8_6, python3-perf 4.18.0-372.221.1.el8_6, +8 more
    fixed: vendor fix RHSA-2026:79783
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.175.1.el8_8, kernel 4.18.0-477.175.1.el8_8, bpftool 4.18.0-477.175.1.el8_8, kernel-core 4.18.0-477.175.1.el8_8, kernel-tools 4.18.0-477.175.1.el8_8, python3-perf 4.18.0-477.175.1.el8_8, +9 more
    fixed: vendor fix RHSA-2026:84793
  • Red Hat Enterprise Linux BaseOS E4S (v.9.2) bpftool 7.0.0-284.200.1.el9_2, kernel 5.14.0-284.200.1.el9_2, kernel-64k 5.14.0-284.200.1.el9_2, kernel-core 5.14.0-284.200.1.el9_2, kernel-tools 5.14.0-284.200.1.el9_2, python3-perf 5.14.0-284.200.1.el9_2, +28 more
    fixed: vendor fix RHSA-2026:92993
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.158.1.el9_4, kernel 5.14.0-427.158.1.el9_4, kernel-64k 5.14.0-427.158.1.el9_4, kernel-core 5.14.0-427.158.1.el9_4, kernel-tools 5.14.0-427.158.1.el9_4, python3-perf 5.14.0-427.158.1.el9_4, +28 more
    fixed: vendor fix RHSA-2026:91489
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.152.1.el9_6, kernel-64k 5.14.0-570.152.1.el9_6, kernel-core 5.14.0-570.152.1.el9_6, kernel-tools 5.14.0-570.152.1.el9_6, kernel-modules 5.14.0-570.152.1.el9_6, kernel-64k-core 5.14.0-570.152.1.el9_6, +27 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) perf 4.18.0-372.221.1.el8_6, kernel 4.18.0-372.221.1.el8_6, bpftool 4.18.0-372.221.1.el8_6, kernel-core 4.18.0-372.221.1.el8_6, kernel-tools 4.18.0-372.221.1.el8_6, python3-perf 4.18.0-372.221.1.el8_6, +8 more
    fixed: vendor fix RHSA-2026:79783
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.175.1.el8_8, kernel 4.18.0-477.175.1.el8_8, bpftool 4.18.0-477.175.1.el8_8, kernel-core 4.18.0-477.175.1.el8_8, kernel-tools 4.18.0-477.175.1.el8_8, python3-perf 4.18.0-477.175.1.el8_8, +8 more
    fixed: vendor fix RHSA-2026:84793
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.51.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.51.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.51.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.51.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.51.1.el9_8
    fixed: vendor fix RHSA-2026:71232
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.59.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.59.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.59.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.59.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.59.1.el10_2
    fixed: vendor fix RHSA-2026:71233
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.163.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.163.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.163.1.el8_10
    fixed: vendor fix RHSA-2026:67468
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-kvm 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-core 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-modules 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-debug-kvm 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-debug-core 4.18.0-553.163.1.rt7.504.el8_10, +4 more
    fixed: vendor fix RHSA-2026:67469
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.51.1.el9_8, kernel-rt-64k 5.14.0-687.51.1.el9_8, kernel-rt-core 5.14.0-687.51.1.el9_8, kernel-rt-modules 5.14.0-687.51.1.el9_8, kernel-rt-64k-core 5.14.0-687.51.1.el9_8, kernel-rt-debug-core 5.14.0-687.51.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:71232
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.59.1.el10_2, kernel-rt-64k 6.12.0-211.59.1.el10_2, kernel-rt-core 6.12.0-211.59.1.el10_2, kernel-rt-modules 6.12.0-211.59.1.el10_2, kernel-rt-64k-core 6.12.0-211.59.1.el10_2, kernel-rt-debug-core 6.12.0-211.59.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:71233
  • Red Hat Enterprise Linux Real Time E4S (v.9.2) kernel-rt 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-core 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-modules 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-debug-core 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-modules-core 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-debug-modules 5.14.0-284.200.1.rt14.485.el9_2, +4 more
    fixed: vendor fix RHSA-2026:93047
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.158.1.el9_4, kernel-rt-core 5.14.0-427.158.1.el9_4, kernel-rt-modules 5.14.0-427.158.1.el9_4, kernel-rt-debug-core 5.14.0-427.158.1.el9_4, kernel-rt-modules-core 5.14.0-427.158.1.el9_4, kernel-rt-debug-modules 5.14.0-427.158.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:91489
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.152.1.el9_6, kernel-rt-64k 5.14.0-570.152.1.el9_6, kernel-rt-core 5.14.0-570.152.1.el9_6, kernel-rt-modules 5.14.0-570.152.1.el9_6, kernel-rt-64k-core 5.14.0-570.152.1.el9_6, kernel-rt-debug-core 5.14.0-570.152.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.51.1.el9_8, kernel-rt-core 5.14.0-687.51.1.el9_8, kernel-rt-modules 5.14.0-687.51.1.el9_8, kernel-rt-debug-core 5.14.0-687.51.1.el9_8, kernel-rt-modules-core 5.14.0-687.51.1.el9_8, kernel-rt-debug-modules 5.14.0-687.51.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:71232
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.59.1.el10_2, kernel-rt-core 6.12.0-211.59.1.el10_2, kernel-rt-modules 6.12.0-211.59.1.el10_2, kernel-rt-debug-core 6.12.0-211.59.1.el10_2, kernel-rt-modules-core 6.12.0-211.59.1.el10_2, kernel-rt-debug-modules 6.12.0-211.59.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:71233
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2) kernel-rt 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-kvm 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-core 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-modules 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-debug-kvm 5.14.0-284.200.1.rt14.485.el9_2, kernel-rt-debug-core 5.14.0-284.200.1.rt14.485.el9_2, +6 more
    fixed: vendor fix RHSA-2026:93047
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.158.1.el9_4, kernel-rt-kvm 5.14.0-427.158.1.el9_4, kernel-rt-core 5.14.0-427.158.1.el9_4, kernel-rt-modules 5.14.0-427.158.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.158.1.el9_4, kernel-rt-debug-core 5.14.0-427.158.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:91489
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.152.1.el9_6, kernel-rt-kvm 5.14.0-570.152.1.el9_6, kernel-rt-core 5.14.0-570.152.1.el9_6, kernel-rt-modules 5.14.0-570.152.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.152.1.el9_6, kernel-rt-debug-core 5.14.0-570.152.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:91492
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-core 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-modules 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-debug-core 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-debug-modules 4.18.0-553.163.1.rt7.504.el8_10, kernel-rt-modules-extra 4.18.0-553.163.1.rt7.504.el8_10, +2 more
    fixed: vendor fix RHSA-2026:67469
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

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

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-416 Use After Free
Technology feeds

References

Sources

Fencer Vulns 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.