KVM SVM checks wrong MSR bitmap for nested guests in Linux kernel
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel's KVM SVM code uses the wrong MSR permission bitmap when it checks whether an MSR access is intercepted while a nested guest is active. The source attributes this to assuming vmcb02's bitmap is always in use, when KVM uses msrpm02 only if L1 wants to intercept MSR accesses.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Use the active VMCB's MSR bitmap when checking if MSR is intercepted Use the MSR permission bitmap of the active VMCB instead of assuming that KVM is always using vmcb02's bitmap when L2 is active, as KVM uses msrpm02 if and only if L1 wants to intercept MSR accesses, i.e. if and only if KVM needs to merge msprm01 with msrpm12. Don't bother tracking the virtual address of the bitmap that's being used, as __va() is cheap on x86, and caching the virtual address would introduce yet another source of potentially stale information.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Fixed versions for the Linux kernel are 3.17, 4.5, 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10 and 7.3. Red Hat lists Red Hat Enterprise Linux 8, 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 as affected with no fix available.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) Fixed in 3.17, 4.5
- Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98716
- 2026-10-18 Alias added: GHSA-hpgm-5w85-35mm
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@84da7a0e92207444d9cbfe69965e17db29008f27 · CNA
- 2026-10-21 1 new reference · CNA
- 2026-10-23 Affected versions changed · Red Hat
- 2026-10-23 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 Fix available: Linux/Linux@001c78bc64389cabe4f9015ab3942ec9c3592caa, Linux/Linux@0e79ebf6f92a7d15187aede44204fa04b93e474c, Linux/[email protected] +3 · CNA
- 2026-10-30 3 new references · CNA
References
Other 8
- https://git.kernel.org/stable/c/001c78bc64389cabe4f9015ab3942ec9c3592caa
- https://git.kernel.org/stable/c/552a110c403f1a61eba0bf71519c6585d9d4242d
- https://git.kernel.org/stable/c/0e79ebf6f92a7d15187aede44204fa04b93e474c
- https://git.kernel.org/stable/c/84da7a0e92207444d9cbfe69965e17db29008f27
- https://git.kernel.org/stable/c/74836ae4785b9754bb36d0b18fcc1dec4e5e98d2
- https://git.kernel.org/stable/c/318ef696fa3c712e46bb62a1a828c3cd62f390c3
- https://git.kernel.org/stable/c/55865b3ae03705aa39198783b9cb1f8b96eb44e4
- https://git.kernel.org/stable/c/9e06bbb9ade7cdf28d4a3b5b14e5812881c8df85
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- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-98716 · CVE Program
- CVE-2026-98716 · NVD
- FIRST EPSS
- GHSA-hpgm-5w85-35mm · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98716 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences