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Fencer Vulns
high 7.1

CVE-2025-40038 json

KVM: SVM: Skip fastpath emulation on VM-Exit if next RIP isn't valid

published 2025-10-28 12 mo ago modified 2026-10-19 20 d ago also EUVD-2025-36490

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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

KVM: SVM: Skip fastpath emulation on VM-Exit if next RIP isn't valid

Skip the WRMSR and HLT fastpaths in SVM's VM-Exit handler if the next RIP isn't valid, e.g. because KVM is running with nrips=false. SVM must decode and emulate to skip the instruction if the CPU doesn't provide the next RIP, and getting the instruction bytes to decode requires reading guest memory. Reading guest memory through the emulator can fault, i.e. can sleep, which is disallowed since the fastpath handlers run with IRQs disabled.

BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:106 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 32611, name: qemu preempt_count: 1, expected: 0 INFO: lockdep is turned off. irq event stamp: 30580 hardirqs last enabled at (30579): [<ffffffffc08b2527>] vcpu_run+0x1787/0x1db0 [kvm] hardirqs last disabled at (30580): [<ffffffffb4f62e32>] __schedule+0x1e2/0xed0 softirqs last enabled at (30570): [<ffffffffb4247a64>] fpu_swap_kvm_fpstate+0x44/0x210 softirqs last disabled at (30568): [<ffffffffb4247a64>] fpu_swap_kvm_fpstate+0x44/0x210 CPU: 298 UID: 0 PID: 32611 Comm: qemu Tainted: G U 6.16.0-smp--e6c618b51cfe-sleep #782 NONE Tainted: [U]=USER Hardware name: Google Astoria-Turin/astoria, BIOS 0.20241223.2-0 01/17/2025 Call Trace: <TASK> dump_stack_lvl+0x7d/0xb0 __might_resched+0x271/0x290 __might_fault+0x28/0x80 kvm_vcpu_read_guest_page+0x8d/0xc0 [kvm] kvm_fetch_guest_virt+0x92/0xc0 [kvm] __do_insn_fetch_bytes+0xf3/0x1e0 [kvm] x86_decode_insn+0xd1/0x1010 [kvm] x86_emulate_instruction+0x105/0x810 [kvm] __svm_skip_emulated_instruction+0xc4/0x140 [kvm_amd] handle_fastpath_invd+0xc4/0x1a0 [kvm] vcpu_run+0x11a1/0x1db0 [kvm] kvm_arch_vcpu_ioctl_run+0x5cc/0x730 [kvm] kvm_vcpu_ioctl+0x578/0x6a0 [kvm] __se_sys_ioctl+0x6d/0xb0 do_syscall_64+0x8a/0x2c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f479d57a94b </TASK>

Note, this is essentially a reapply of commit 5c30e8101e8d ("KVM: SVM: Skip WRMSR fastpath on VM-Exit if next RIP isn't valid"), but with different justification (KVM now grabs SRCU when skipping the instruction for other reasons).

Patch / fix

  • Linux Linux 6.6.113, 6.12.53, 6.17.3, 6.18
  • linux Debian 13 6.12.57-1
  • linux Debian 14 6.17.6-1

debian advisories DEBIAN-CVE-2025-40038

  • linux Ubuntu 24.04 LTS 6.8.0-106.106
  • linux Ubuntu 25.10 6.17.0-14.14
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1050.53
  • linux-aws Ubuntu 25.10 6.17.0-1007.7
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1052.55
  • linux-gcp Ubuntu 25.10 6.17.0-1007.7
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1048.53
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1049.49

ubuntu advisories UBUNTU-CVE-2025-40038

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1.21.15
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.61.1
  • kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.61.1

suse advisories SUSE-SU-2026:20473-1SUSE-SU-2026:20496-1SUSE-SU-2026:20039-1SUSE-SU-2026:20059-1SUSE-SU-2025:4521-1SUSE-SU-2025:4517-1

  • kernel-source-longterm openSUSE Tumbleweed 6.18.16-1.1
  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.8.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.8.1

opensuse advisories openSUSE-SU-2026:10301-1openSUSE-SU-2025:20172-1openSUSE-SU-2025:15702-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-40038 updated cvss 6.1

kernel: KVM: SVM: Skip fastpath emulation on VM-Exit if next RIP isn't valid

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
24 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.