# CVE-2026-46113 — Linux

> As of 2026-10-03, CVE-2026-46113 is a HIGH-severity vulnerability in Linux, CVSS v3.1 8.8, EPSS 0.1% (4.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-46113, most recently “CVE-2026-53359 ("Januscape") - 16-Year-Old Linux KVM Shadow MMU Use-After-Free Exploited as Zero-Day”.

**Last updated:** 2026-10-03

## What is CVE-2026-46113?

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Fix shadow paging use-after-free due to unexpected GFN The shadow MMU computes GFNs for direct shadow pages using sp->gfn plus the SPTE index. This assumption breaks for shadow paging if the guest page tables are modified between VM entries (similar to commit aad885e77496, "KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE", 2026-03-27). The flow is as follows: - a PDE is installed for a 2MB mapping, and a page in that area is accessed. KVM creates a kvm_mmu_page consisting of 512 4KB pages; the kvm_mmu_page is marked by FNAME(fetch) as direct-mapped because the guest's mapping is a huge page (and thus contiguous). - the PDE mapping is changed from outside the guest. - the guest accesses another page in the same 2MB area. KVM installs a new leaf SPTE and rmap entry; the SPTE uses the "correct" GFN (i.e. based on the new mapping, as changed in the previous step) but that GFN is outside of the [sp->gfn, sp->gfn + 511] range; therefore the rmap entry cannot be found and removed when the kvm_mmu_page is zapped. - the memslot that covers the first 2MB mapping is deleted, and the kvm_mmu_page for the now-invalid GPA is zapped. However, rmap_remove() only looks at the [sp->gfn, sp->gfn + 511] range established in step 1, and fails to find the rmap entry that was recorded by step 3. - any operation that causes an rmap walk for the same page accessed by step 3 then walks a stale rmap and dereferences a freed kvm_mmu_page. This includes dirty logging or MMU notifier invalidations (e.g., from MADV_DONTNEED). The underlying issue is that KVM's walking of shadow PTEs assumes that if a SPTE is present when KVM wants to install a non-leaf SPTE, then the existing kvm_mmu_page must be for the correct gfn. Because the only way for the gfn to be wrong is if KVM messed up and failed to zap a SPTE... which shouldn't happen, but *actually* only happens in response to a guest write. That bug dates back literally forever, as even the first version of KVM assumes that the GFN matches and walks into the "wrong" shadow page. However, that was only an imprecision until 2032a93d66fa ("KVM: MMU: Don't allocate gfns page for direct mmu pages") came along. Fix it by checking for a target gfn mismatch and zapping the existing SPTE. That way the old SP and rmap entries are gone, KVM installs the rmap in the right location, and everyone is happy.

The record classifies CVE-2026-46113 under weakness class [CWE-416](https://intel.threadlinqs.com/cwe/CWE-416). Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 153 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.8 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 4.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-05-28, last modified 2026-10-03

## Is CVE-2026-46113 being exploited?

It currently carries a trending score of 6 in the Threadlinqs vulnerability feed.

## Affected products and versions

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

## How to fix CVE-2026-46113

The record marks a vendor fix as available for CVE-2026-46113. Patch reference: [https://git.kernel.org/stable/c/06c19c967b845b63172601fe459667d973b7e6b7](https://git.kernel.org/stable/c/06c19c967b845b63172601fe459667d973b7e6b7). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-46113

1 tracked threat in the Threadlinqs corpus references CVE-2026-46113, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CVE-2026-53359 ("Januscape") - 16-Year-Old Linux KVM Shadow MMU Use-After-Free Exploited as Zero-Day](https://intel.threadlinqs.com/threat/TL-2026-1189) — HIGH · 2026-07-10

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-11. 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/9597963a8ca16259d194a1d9950d7bd22a10ab2f)
- [git.kernel.org (e9d4ea13aa2b6400bb10ec64b370ba3dadcd22f0)](https://git.kernel.org/stable/c/e9d4ea13aa2b6400bb10ec64b370ba3dadcd22f0)
- [git.kernel.org (488e386484ec8c0e558be6e156edf34ed9f4d5c8)](https://git.kernel.org/stable/c/488e386484ec8c0e558be6e156edf34ed9f4d5c8)
- [git.kernel.org (06c19c967b845b63172601fe459667d973b7e6b7)](https://git.kernel.org/stable/c/06c19c967b845b63172601fe459667d973b7e6b7)
- [git.kernel.org (738ec97b1855df6c08fe2369f798fa0b972e556b)](https://git.kernel.org/stable/c/738ec97b1855df6c08fe2369f798fa0b972e556b)

_Showing 5 of 7 recorded references._

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-46113
Full detection coverage and IOCs for threats exploiting CVE-2026-46113 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp