# CVE-2026-89907: LoongArch: KVM: Validate MSI data before routing it to EIOINTC

> A missing validation in the LoongArch KVM module allows userspace to corrupt kernel memory via MSI data, potentially leading to privilege escalation or code execution.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89907, DEBIAN-CVE-2026-89907, GHSA-fvq2-363j-rc9x, UBUNTU-CVE-2026-89907

## What is CVE-2026-89907?

CVE-2026-89907 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

LoongArch: KVM: Validate MSI data before routing it to EIOINTC

pch_msi_set_irq() passes e->msi.data straight into eiointc_set_irq() as
the irq number. The MSI data comes from userspace, that either via a
KVM_IRQ_ROUTING_MSI entry set with KVM_SET_GSI_ROUTING (used by irqfd
and KVM_IRQ_LINE) or directly via KVM_SIGNAL_MSI, and is never checked
against EIOINTC_IRQS.

eiointc_set_irq() uses the value with __set_bit()/__clear_bit() on the
256-bit isr bitmap, eiointc_update_irq() then indexes sw_coremap[] and
the per-cpu coreisr/sw_coreisr bitmaps with it. Therefore a data value
>= 256 reads and writes memory past the end of those arrays, i.e. any
process holding a VM fd can corrupt kernel memory beyond the allocation
of loongarch_eiointc.

Reject MSI data that doesn't fit in the EIOINTC irq space. The DMSINTC
path is unaffected as it decodes the vector from the address and masks
it.

## Which versions are affected by CVE-2026-89907?


## How do I fix CVE-2026-89907?

Apply the vendor's patch.

## Is CVE-2026-89907 being exploited?

There is no known exploitation of CVE-2026-89907 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89907 and fix it if it is affected.

What it is: CVE-2026-89907 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89907 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89907/ (Markdown: https://insights.sbomify.com/CVE-2026-89907/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89907
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89907
- OSV: https://osv.dev/vulnerability/CVE-2026-89907

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89907/
Summaries are generated and may contain mistakes; the official description above is the record.