CVE-2026-74516: KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active
Noroxi assessment
Priority: Monitor (action score 32/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
- Someone with local access to the system can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Linux Linux 4ca05385b3ddbd463be17c6d69ec76fca657081d, 6664a5aea45318f4ec156a729949b474dd6e3159, 7668c58dcf465559dc7a0d2e95e9cb79cf47454b; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 4ca05385b3ddbd463be17c6d69ec76fca657081d, 6664a5aea45318f4ec156a729949b474dd6e3159, 7668c58dcf465559dc7a0d2e95e9cb79cf47454b; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active Always update x2APIC MSR intercepts for L1 when AVIC is deactivated, even if L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC is fully enabled prior to running L2, and is then inhibited while L2 is active (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled, but with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of the host's APIC state, send arbitrary interrupts, change task priority, and ultimately trivially DoS the host. E.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with CONFIG_HYPERV=n in the host kernel as a "safe" PoC, yields: Spurious interrupt (vector 0xee) on CPU#425. Acked And hacking KVM to abuse kvm_set_posted_intr_wakeup_handler() to register a handler and WARN on POSTED_INTR_WAKEUP_VECTOR yields: ------------[ cut here ]------------ WARNING: arch/x86/kvm/svm/svm.c:5594 at pi_wakeup_handler+0x9/0x10 [kvm_amd], CPU#156: nested_x2apic_t/316940 CPU: 156 UID: 0 PID: 316940 Comm: nested_x2apic_t Tainted: G S U Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER Hardware name: Google Astoria-Turin/astoria, BIOS 0.20260209.0-0 02/09/2026 RIP: 0010:pi_wakeup_handler+0x9/0x10 [kvm_amd] Call Trace: <IRQ> sysvec_kvm_posted_intr_wakeup_ipi+0x64/0x80 </IRQ> <TASK> asm_sysvec_kvm_posted_intr_wakeup_ipi+0x1a/0x20 RIP: 0010:vcpu_run+0x1430/0x1e40 [kvm] kvm_arch_vcpu_ioctl_run+0x2c1/0x600 [kvm] kvm_vcpu_ioctl+0x580/0x6b0 [kvm] __se_sys_ioctl+0x6d/0xb0 do_syscall_64+0x10a/0x480 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x46ff4b </TASK> ---[ end trace 0000000000000000 ]---
- Published
- Aug 15, 2026
- Updated
- Oct 16, 2026
- EPSS
- 0.1% · 3th percentile
- CWE
- —
Report tools
Action score
32
Low priority for now.
- CVSS
- 32 / 40 · 8.2 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Linux
- 8.2
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 6.0affected
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before 4ca05385b3ddbd463be17c6d69ec76fca657081daffected · git
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before 6664a5aea45318f4ec156a729949b474dd6e3159affected · git
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before f12373625b4dc9bcc89c41872648878c73bb9272affected · git
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before 7668c58dcf465559dc7a0d2e95e9cb79cf47454baffected · git
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before 89f9e8398e79c49886766fc24a84c37726231104affected · git
- 091abbf578f926e763adc0f577baeb7f405b4bdc and later · before 7d3aae206663c4e006b25a1c7a20a4029e67da76affected · git
- before 6.0not affected · semver
- 6.1.183 and later · up to and including 6.1.*not affected · semver
- 6.6.151 and later · up to and including 6.6.*not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | bpftool | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-abi-stablelists | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-core | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-cross-headers | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-debug | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-debug-core | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-debug-devel | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-debug-modules | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-debug-modules-extra | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-devel | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-doc | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-headers | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-modules | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-modules-extra | before 4.18.0-553.171.1.el8_10 | 4.18.0-553.171.1.el8_10 |
| AlmaLinux:8 | kernel-rt | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-core | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-debug | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-core | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-devel | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-modules | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-modules-extra | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-devel | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
| AlmaLinux:8 | kernel-rt-modules | before 4.18.0-553.171.1.rt7.512.el8_10 | 4.18.0-553.171.1.rt7.512.el8_10 |
+66
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation40Plan
- CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment40Plan
- CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()40Plan
Published before and after this one in the same product
- ← EarlierCVE-2026-74513Aug 15, 2026 · dibs: fix use-after-free of dmb_node in loopback attach/detach/unregister31Monitor
- ← EarlierCVE-2026-74515Aug 15, 2026 · KVM: s390: pci: Reject adapter interrupt forwarding if already enabled35Monitor
- Later →CVE-2026-74517Aug 15, 2026 · KVM: x86: Cancel delayed I/O APIC EOI handling before destroying vCPUs37Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 4ca05385b3ddbd463be17c6d69ec76fca657081d | Vendor (CNA) |
| Linux Linux | 6664a5aea45318f4ec156a729949b474dd6e3159 | Vendor (CNA) |
| Linux Linux | 7668c58dcf465559dc7a0d2e95e9cb79cf47454b | Vendor (CNA) |
| Linux Linux | 7d3aae206663c4e006b25a1c7a20a4029e67da76 | Vendor (CNA) |
| Linux Linux | 89f9e8398e79c49886766fc24a84c37726231104 | Vendor (CNA) |
| Linux Linux | f12373625b4dc9bcc89c41872648878c73bb9272 | Vendor (CNA) |
| azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 | 6.6.152.1-1 · Release Notes | Microsoft (MSRC) |
| almalinux:bpftool | 4.18.0-553.171.1.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel | 4.18.0-553.171.1.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-core | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-core | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-devel | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-modules | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-modules-extra | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-devel | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-modules | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-modules-extra | 4.18.0-553.171.1.rt7.512.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| debian:linux | 6.1.187-1 · Debian:12 | Package registry (OSV) |
| debian:linux-6.12 | 6.12.107-1~deb12u1 · Debian:12 | Package registry (OSV) |
| red hat:kernel-rt | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-core | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-core | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-debuginfo | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-devel | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-kvm | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-modules | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-modules-extra | 0:4.18.0-553.171.1.rt7.512.el8_10 · Red Hat:enterprise_linux:8::nfv | Package registry (OSV) |
+5
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-0854 · Aug 19, 2026(Linux Kernel Güvenlik Bildirimi)
Not on record for this CVE: patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
—
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log (2)
- SSVC exploitation— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (5 more)Show less
- git.kernel.org/stable/c/6664a5aea45318f4ec156a729949b474dd6e3159
- git.kernel.org/stable/c/7668c58dcf465559dc7a0d2e95e9cb79cf47454b
- git.kernel.org/stable/c/7d3aae206663c4e006b25a1c7a20a4029e67da76
- git.kernel.org/stable/c/89f9e8398e79c49886766fc24a84c37726231104
- git.kernel.org/stable/c/f12373625b4dc9bcc89c41872648878c73bb9272
Vendor advisories and official records. Exploit/PoC links are deliberately left out.