# CVE-2026-89513

## Summary

- **CVE ID:** CVE-2026-89513
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## Description

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

RISC-V: KVM: Fix PMU event info array size overflow

SBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo)
in a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010
truncate to 16. KVM then allocates one entry but loops over the original
num_events, causing out-of-bounds reads and writes. A nested guest
triggered:

BUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142
Read of size 4 at addr ff600000074d46b0 by task init/1
Call Trace:
[<ffffffff8006471c>] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142
[<ffffffff800690c0>] kvm_sbi_ext_pmu_handler+0xca/0x268
[<ffffffff8006779e>] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6
[<ffffffff8006008c>] kvm_riscv_vcpu_exit+0x48c/0x540
[<ffffffff8005ea0a>] kvm_arch_vcpu_ioctl_run+0x37e/0xc80
Allocated by task 1:
 __kmalloc_noprof+0x19e/0x4b0
 kvm_riscv_vcpu_pmu_event_info+0x72/0x142
 kvm_sbi_ext_pmu_handler+0xca/0x268
 kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6
 kvm_riscv_vcpu_exit+0x48c/0x540
 kvm_arch_vcpu_ioctl_run+0x37e/0xc80
The buggy address is located 0 bytes to the right of
 allocated 16-byte region [ff600000074d46a0, ff600000074d46b0)

Store the shared-memory size in size_t and reject multiplication overflow.
Allocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged
to kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings.
Use kvcalloc() to allow vmalloc fallback and an unsigned long loop index
to match num_events.

## Affected Products

- Linux — Linux (e309fd113b9f6c34672a487be08fecb7e12e7e29)
- Linux — Linux (6.18)
- Linux — Linux (0)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/82088f88c96b99c27a974d09b02c2b133262fadf)
- [CNA](https://git.kernel.org/stable/c/735bc20c24187ca419c9d5e63860a54b91be34bd)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.12%
- **EPSS Percentile:** 2.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._