RISC-V: KVM: Synchronize hrtimer callback during teardown
Assessment
- Severity
- Moderate
- CVSS base score
- 6.5CVSS:3.1/
AV:L/ AC:H/ PR:L/ UI:N/ S:U/ C:L/ I:H/ A:H - Impact
- Not stated
- EPSS, next 30 days
- Not scored yet
- Public exploit code
- No Nuclei template lists it
- Exploitability
- Not assessed
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Mariner
- Weakness
- —
- Issued by
- Linux
- Published
- 20 Oct 2026 · October 2026
- Last revised
- 24 Oct 2026Information published.
- Attack vector
- LocalAV:L
- Attack complexity
- HighAC:H
- Privileges required
- LowPR:L
- User interaction
- NoneUI:N
- Scope
- UnchangedS:U
- Confidentiality
- LowC:L
- Integrity
- HighI:H
- Availability
- HighA:H
Updates that fix it
0 KBsNo KB listed
MSRC lists no downloadable update, which usually means a service-side fix or a release-notes update. Check the MSRC advisory.
Affected products
1 affected product
- azl3 kernel 6.6.157.1-1 on Azure Linux 3.0
What changed
First observed 21 Oct 2026- 25 Oct 2026 · 07:41:18 UTC Last revised21 Oct 2026 18:34 UTC → 24 Oct 2026 14:47 UTC
- 23 Oct 2026 · 09:33:49 UTC Public exploit codeUnknown: exploit-code evidence is incomplete or retained → No Nuclei template listed
- 23 Oct 2026 · 09:33:49 UTC CISA KEVUnknown: catalog evidence is incomplete or retained → Not listed in the collected catalog
- 23 Oct 2026 · 09:33:49 UTC Source coverage: public-exploit-codeIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: first-epssIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
- 23 Oct 2026 · 09:33:49 UTC Source coverage: msrc-cvrfIncomplete → Current
- 23 Oct 2026 · 08:31:50 UTC Public exploit codeNo Nuclei template listed → Unknown: exploit-code evidence is incomplete or retained
- 23 Oct 2026 · 08:31:50 UTC CISA KEVNot listed in the collected catalog → Unknown: catalog evidence is incomplete or retained
- 23 Oct 2026 · 08:31:50 UTC Source coverage: public-exploit-codeCurrent → Incomplete
- 23 Oct 2026 · 08:31:50 UTC Source coverage: first-epssCurrent → Incomplete
- 23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete
Show 2 more recent changes
- 23 Oct 2026 · 08:31:50 UTCSource coverage: msrc-cvrf Current → Incomplete
- 21 Oct 2026 · 20:45:25 UTCLast revised 20 Oct 2026 14:43 UTC → 21 Oct 2026 18:34 UTC
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Explore global source statements, affected packages and advisory history for CVE-2026-98464. The catalog has a separate collection scope from Microsoft release records.
Collected exploitation and prediction evidence
Risk source coverageCISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.
No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.
cve-program · CVE-2026-98464
PublishedRISC-V: KVM: Synchronize hrtimer callback during teardown
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.
- Source published
- 18 Oct 2026 15:15:16 UTC
- Source modified
- 24 Oct 2026 14:08:56 UTC
- Observed here
- 24 Oct 2026 16:17:04 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
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CVSS 3.1 · 9.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H