# CVE-2026-64186 — Linux

> As of 2026-07-19, CVE-2026-64186 is a vulnerability in Linux, EPSS 0.1% (5.0th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-64186 as of 2026-07-19; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-19

## What is CVE-2026-64186?

In the Linux kernel, the following vulnerability has been resolved: iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs In iommu_mmio_write() and iommu_capability_write(), the variables dbg_mmio_offset and dbg_cap_offset are declared as int. However, they are populated using kstrtou32_from_user(). If a user provides a sufficiently large value, it can become a negative integer. Prior to this patch, the AMD IOMMU debugfs implementation was already protected by different mechanisms. 1. #define OFS_IN_SZ 8 ensures the user string OFS_IN_SZ) return -EINVAL; 2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int and iommu->mmio_phys_end is u64 if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64)) return -EINVAL; 3. The show handlers would currently catch the negative number and refuse to perform the read. Replace kstrtou32_from_user() with kstrtos32_from_user() to parse the input, and check for negative values to explicitly prevent out-of-bounds memory accesses directly in iommu_mmio_write() and iommu_capability_write().

1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 78 days ago.

## Severity and exploitation probability

- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 5.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 0.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-19

## Is CVE-2026-64186 being exploited?

It currently carries a trending score of 31 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Linux](https://intel.threadlinqs.com/vendors/linux): Linux

## How to fix CVE-2026-64186

No vendor patch reference has been recorded for CVE-2026-64186 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-64186

No threat campaign in the Threadlinqs corpus currently references CVE-2026-64186, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-07-21. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [git.kernel.org](https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407)
- [git.kernel.org (62f9dfbf1aceae88b03c5ca08f7d36e943939dec)](https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec)
- [git.kernel.org (8dfd3d8d74435344ee8dc9237596959c8b2a6cbe)](https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-64186
Full detection coverage and IOCs for threats exploiting CVE-2026-64186 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp