In the Linux kernel, the following vulnerability has been resolved:
cpuset: fix warning when disabling remote partition
A warning was triggered as follows:
WARNING: kernel/cgroup/cpuset.c:1651 at remote_partition_disable+0xf7/0x110
RIP: 0010:remote_partition_disable+0xf7/0x110
RSP: 0018:ffffc90001947d88 EFLAGS: 00000206
RAX: 0000000000007fff RBX: ffff888103b6e000 RCX: 0000000000006f40
RDX: 0000000000006f00 RSI: ffffc90001947da8 RDI: ffff888103b6e000
RBP: ffff888103b6e000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: ffff88810b2e2728 R12: ffffc90001947da8
R13: 0000000000000000 R14: ffffc90001947da8 R15: ffff8881081f1c00
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f55c8bbe0b2 CR3: 000000010b14c000 CR4: 00000000000006f0
Call Trace:
update_prstate+0x2d3/0x580
cpuset_partition_write+0x94/0xf0
kernfs_fop_write_iter+0x147/0x200
vfs_write+0x35d/0x500
ksys_write+0x66/0xe0
do_syscall_64+0x6b/0x390
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f55c8cd4887
Reproduction steps (on a 16-CPU machine):
# cd /sys/fs/cgroup/
# mkdir A1
# echo +cpuset > A1/cgroup.subtree_control
# echo "0-14" > A1/cpuset.cpus.exclusive
# mkdir A1/A2
# echo "0-14" > A1/A2/cpuset.cpus.exclusive
# echo "root" > A1/A2/cpuset.cpus.partition
# echo 0 > /sys/devices/system/cpu/cpu15/online
# echo member > A1/A2/cpuset.cpus.partition
When CPU 15 is offlined, subpartitions_cpus gets cleared because no CPUs
remain available for the top_cpuset, forcing partitions to share CPUs with
the top_cpuset. In this scenario, disabling the remote partition triggers
a warning stating that effective_xcpus is not a subset of
subpartitions_cpus. Partitions should be invalidated in this case to
inform users that the partition is now invalid(cpus are shared with
top_cpuset).
To fix this issue:
- Only emit the warning only if subpartitions_cpus is not empty and the
effective_xcpus is not a subset of subpartitions_cpus.
- During the CPU hotplug process, invalidate partitions if
subpartitions_cpus is empty.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-05). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it