CVE-2025-37936perf/x86/intel: KVM: Mask PEBS_ENABLE loaded for guest with vCPU's value.
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel: KVM: Mask PEBS_ENABLE loaded for guest with vCPU's value. When generating the MSR_IA32_PEBS_ENABLE value that will be loaded on VM-Entry to a KVM guest, mask the value with the vCPU's desired PEBS_ENABLE value. Consulting only the host kernel's host vs. guest masks results in running the guest with PEBS enabled even when the guest doesn't want to use PEBS. Because KVM uses perf events to proxy the guest virtual PMU, simply looking at exclude_host can't differentiate between events created by host userspace, and events created by KVM on behalf of the guest. Running the guest with PEBS unexpectedly enabled typically manifests as crashes due to a near-infinite stream of #PFs. E.g. if the guest hasn't written MSR_IA32_DS_AREA, the CPU will hit page faults on address '0' when trying to record PEBS events. The issue is most easily reproduced by running `perf kvm top` from before commit 7b100989b4f6 ("perf evlist: Remove __evlist__add_default") (after which, `perf kvm top` effectively stopped using PEBS). The userspace side of perf creates a guest-only PEBS event, which intel_guest_get_msrs() misconstrues a guest-*owned* PEBS event. Arguably, this is a userspace bug, as enabling PEBS on guest-only events simply cannot work, and userspace can kill VMs in many other ways (there is no danger to the host). However, even if this is considered to be bad userspace behavior, there's zero downside to perf/KVM restricting PEBS to guest-owned events. Note, commit 854250329c02 ("KVM: x86/pmu: Disable guest PEBS temporarily in two rare situations") fixed the case where host userspace is profiling KVM *and* userspace, but missed the case where userspace is profiling only KVM.
- CVSS
- 8.7 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | from c59a1f106f5cd4843c097069ff1bb2ad72103a67 before 160153cf9e4aa875ad086cc094ce34aac8e13d63; from c59a1f106f5cd4843c097069ff1bb2ad72103a67 before 34b6fa11431aef71045ae5a00d90a7d630597eda; from c59a1f106f5cd4843c097069ff1bb2ad72103a67 before 44ee0afc9d1e7a7c1932698de01362ed80cfc4b5; from c59a1f106f5cd4843c097069ff1bb2ad72103a67 before 86aa62895fc2fb7ab09d7ca40fae8ad09841f66b; from c59a1f106f5cd4843c097069ff1bb2ad72103a67 before 58f6217e5d0132a9f14e401e62796916aa055c1b | CNA record |
linux linux_kernel linux:linux_kernel | from 6.0 before 6.1.138; from 6.2 before 6.6.90; from 6.7 before 6.12.28; from 6.13 before 6.14.6; 6.15; 6.15; 6.15; 6.15 | NVD |
debian debian_linux debian:debian_linux | 11.0 | NVD |
References
- https://git.kernel.org/stable/c/160153cf9e4aa875ad086cc094ce34aac8e13d63patch
- https://git.kernel.org/stable/c/34b6fa11431aef71045ae5a00d90a7d630597edapatch
- https://git.kernel.org/stable/c/44ee0afc9d1e7a7c1932698de01362ed80cfc4b5patch
- https://git.kernel.org/stable/c/86aa62895fc2fb7ab09d7ca40fae8ad09841f66bpatch
- https://git.kernel.org/stable/c/58f6217e5d0132a9f14e401e62796916aa055c1bpatch
- https://lists.debian.org/debian-lts-announce/2025/08/msg00010.htmlthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.