Look up another CVE · open CVE-2026-64286 in the interactive tracker
CVE-2026-64286
KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem arch/arm64. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-64286 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6405-1 · 2026-07-31 · text | 6.12.100-1 | Update the kernel and reboot. DSA-6405-1 shipped the fix on 2026-07-31, in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
flush_hyp_vcpu() copies the host vCPU context into the hyp's private vCPU on every run. ctxt_to_vcpu() expects a guest context to have a NULL __hyp_running_vcpu, which is only ever set on the host context, so that it resolves the vCPU via container_of(). While this is generally the case, flush_hyp_vcpu() copies the context verbatim and does not enforce this, so a value provided by the host is dereferenced at EL2 (host -> EL2). Fix by clearing __hyp_running_vcpu after the copy.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/arm64/kvm/hyp/nvhe/hyp-main.c
- What this is
- KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)MAINTAINERS section matched on arch/arm64/kvm/ · linux-arm-kernel@lists.infradead.org · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-07-25 (3 months ago)source
- CVSS
- 8.2 high
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 6.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- arch/arm64
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.2 | 6.6.145 | 477145860dba |
| 6.2 | 6.12.97 | dfaef40d8a15 |
| 6.2 | 6.18.39 | 6bea2f8becdb |
| 6.2 | 7.1.4 | d4f4d61715d1 |
| 6.2 | 7.2 | e8042f6e1d7b |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DSA-6405-1 | 2026-07-31 | trixie 6.12.100-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- A malicious or compromised local EL1 host can place the pointer in the host vCPU context and trigger the vulnerable pKVM path through KVM_RUN; no remote input path reaches it.
- AC:LAttack complexity, low
- The attacker-selected pointer is copied and dereferenced deterministically on every vCPU run, without a race, and EL2 addresses of host-donated metadata are derivable by the host.
- PR:HPrivileges required, high
- Exploitation requires host-kernel control or an equivalent arbitrary kernel write. The KVM userspace register API does not expose __hyp_running_vcpu, and user namespaces do not bypass this restriction.
- UI:NUser interaction, none
- Once the malicious host context is prepared, invoking the vCPU run path requires no action by another user.
- S:CScope, changed
- The vulnerability crosses the intended isolation boundary from the untrusted EL1 host into the pKVM hypervisor at EL2 and can affect protected-VM resources.
- C:HConfidentiality impact, high
- The forged pointer drives EL2-private memory dereferences during system-register restoration. Chaining these reads with the write-side corruption can compromise EL2 and expose hypervisor or protected-guest memory.
- I:HIntegrity impact, high
- The system-register save path can write through the attacker-selected vCPU pointer into EL2-accessible memory. This can corrupt trusted hypervisor metadata and plausibly enable control-flow or protected-guest state modification.
- A:HAvailability impact, high
- An invalid or unmapped pointer causes a synchronous EL2 fault followed by the nVHE HYP panic handler, which explicitly panics the host kernel.