Vulnerability in Linux kernel (CVE-2026-98220)
Summary
Vulnerability in Linux kernel (CVE-2026-98220). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix NULL sched deref in kfunc sub-sched error paths
When the root scheduler has sub-scheds attached, the COMPAT kfunc
wrappers scx_bpf_select_cpu_and() and scx_bpf_dsq_insert_vtime() refuse
the call and report to @p's scheduler:
scx_error(scx_task_sched(p), "... must be used");
The wrappers are reachable with tasks that have no scheduler.
scx_bpf_select_cpu_and() is in the select_cpu kfunc group, which
scx_kfunc_context_filter() opens to BPF_PROG_TYPE_SYSCALL programs;
scx_bpf_dsq_insert_vtime() is in the enqueue_dispatch group, which
ops.enqueue() and ops.dispatch() may call with any KF_RCU task -- the
group has no kf_tasks validation, and scx_dsq_insert_preamble() checks
task ownership with scx_task_on_sched() precisely because @p may be an
arbitrary task.
scx_task_sched(p) is p->scx.sched, which is NULL for tasks past
sched_ext_dead() -- which clears it via scx_disable_and_exit_task() on
exit -- and for idle tasks, which the enable paths skip as they are
never scheduled through SCX. It is also an rcu_dereference_protected()
that expects @p's pi_lock or rq lock, which neither wrapper holds.
Passing NULL to scx_error() reaches scx_vexit(), which dereferences
sch->exit_info, oopsing the kernel.
One concrete trigger exercised while developing the fix: a
BPF_PROG_TYPE_SYSCALL program calling the select_cpu_and wrapper on an
exited-but-not-reaped task while a sub-scheduler was attached (its pid…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-98220 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-98220" on the vendor's site.
CVE-2026-98220 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-98220
- Ubuntu UBUNTU-CVE-2026-98220 linux-hwe-edge
References
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com