---
cve: "CVE-2026-98464"
severity: "CRITICAL"
cvss: 9.3
epss: "0.1%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-10-18 15:15:16"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-10-27T10:50:07+01:00"
---

# CVE-2026-98464

> 9.3 CRITICAL

## Beschreibung

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

RISC-V: KVM: Synchronize hrtimer callback during teardown

The non-Sstc hrtimer callback clears next_set before its final uses of
the enclosing vCPU.  If teardown observes next_set as false while the
callback is still running, kvm_riscv_vcpu_timer_cancel() skips
hrtimer_cancel() and kvm_destroy_vcpus() can free the vCPU before the
callback enters kvm_riscv_vcpu_set_interrupt().

A guest can arm the timer with SBI TIME and request shutdown with SBI
legacy shutdown or SRST.  A VMM that honors KVM_EXIT_SYSTEM_EVENT and
destroys the VM supplies the teardown side of the race; no post-launch
host ioctl is needed to arm or request teardown.

On upstream master 62cc90241548, generic KASAN reported:

  BUG: KASAN: slab-use-after-free in do_raw_spin_lock
  Write of size 4 at addr ff60000005e58898

  kvm_riscv_vcpu_set_interrupt
  kvm_riscv_vcpu_hrtimer_expired
  __hrtimer_run_queues
  hrtimer_interrupt

The object was allocated by KVM_CREATE_VCPU and freed concurrently by:

  kvm_destroy_vcpus
  kvm_arch_destroy_vm
  kvm_destroy_vm
  __fput

For deterministic validation, I added mdelay(1000) immediately after
the existing next_set = false assignment.  This only widens the
existing post-clear callback window.  A no-delay trace build naturally
reached the callback-after-teardown-start/before-deinit ordering in 12
of 200 runs, but 1,500 stock-kernel stress iterations did not produce a
KASAN report, so natural reproduction is timing-sensitive.

Always invoke hrtimer_cancel() for an initialized timer.  Preserve the
existing -EINVAL result when the timer is no longer set, but only after
synchronizing with a running callback.

With this patch, hrtimer_cancel() blocked for the full widened callback
window before vCPU destruction.  KASAN reported no error in 100
fixed-and-widened runs or 200 fix-only timing-sweep runs.

## CNA-Record (Kanon, cvelistV5)

- CNA: **Linux**
- State: PUBLISHED
- Stand: 2026-10-24 14:08:56
- CNA-CVSS: **9.3** (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.1.189
- Kernel ≥ 6.6.158
- Kernel ≥ 6.12.112
- Kernel ≥ 6.18.55
- Kernel ≥ 7.2.9

## Referenzen

- <https://git.kernel.org/stable/c/9bdbae64ae0dab93041ebc57ec4e93def793fc2d>
- <https://git.kernel.org/stable/c/2af03b606aadaaeb386658ef798c79bdcdef87c1>
- <https://git.kernel.org/stable/c/e66aced74f0122380603c9910a71d77618b28f0e>
- <https://git.kernel.org/stable/c/ea91f05a55b807ead3166546a2c75f4185ca645f>
- <https://git.kernel.org/stable/c/3cc6184bd5920c9685d87f4e260568feba08650d>
- <https://git.kernel.org/stable/c/aaad136d56d91252517272b68cd533e5714698d5>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-98464/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_