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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98164: KVM: x86/mmu: Check write tracking in all address spaces

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 09aa68552d2542cc6c23edd1568ac265dc5d886f, 0f38453cdb2e17566ccb7c0f3dabd5bd21caca26, 429b6f43b4d8c98988fdca99e02dc156134e3d77; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.157.1-1.

Low priority for now. Upgrade to Linux Linux 09aa68552d2542cc6c23edd1568ac265dc5d886f, 0f38453cdb2e17566ccb7c0f3dabd5bd21caca26, 429b6f43b4d8c98988fdca99e02dc156134e3d77; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.157.1-1 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: x86/mmu: Check write tracking in all address spaces kvm_gfn_is_write_tracked() checks only the supplied memslot, but page tracking is per-address-space and shadow pages are shared across all address spaces. With SMM, a GFN can therefore be write-tracked in one address space and appear untracked through the other. Check the supplied slot first, then the slot for the other address space. This ensures all callers honor write tracking regardless of the active address space. In particular, it prevents mmu_try_to_unsync_pages() from marking an upper-level shadow page unsync and eventually triggering the BUG in pte_list_remove(). [invert direction of the conditional. - Paolo]

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 29, 2026
Updated
Oct 7, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
5.5
CNA · Linux
7.1
1.6 point gap

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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.

Follow CVE-2026-98164

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi 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.

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Affected 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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel4.2 and later · before 6.1.187
  • linux linux kernel6.2 and later · before 6.6.156
  • linux linux kernel6.7 and later · before 6.12.108
  • linux linux kernel6.13 and later · before 6.18.49
  • linux linux kernel6.19 and later · before 7.1.13
  • linux linux kernel7.2

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

    • 4.2affected
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before 09aa68552d2542cc6c23edd1568ac265dc5d886faffected · git
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before 429b6f43b4d8c98988fdca99e02dc156134e3d77affected · git
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before d8636c8f9f95d0fd1e2f6f1cad0d5757aa6f212aaffected · git
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before c0a9bd5fca0b5f2dea32b0fc31350e71e8648112affected · git
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before ec8fcaf354c1cbb36755d48e9f5a00c9591349e5affected · git
    • 699023e239658e62da6f42f47d31b54788521ec1 and later · before 0f38453cdb2e17566ccb7c0f3dabd5bd21caca26affected · git
    • before 4.2not affected · semver
    • 6.1.187 and later · up to and including 6.1.*not affected · semver
    • 6.6.156 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.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.1.13-17.1.13-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-98161Sep 25, 2026 · nvdimm: pmem: keep PREFLUSH before data writes
    22Monitor
  • ← EarlierCVE-2026-98162Sep 25, 2026 · smb/server: fix tree connection leak in smb2_tree_connect()
    22Monitor
  • ← EarlierCVE-2026-98163Sep 26, 2026 · cgroup: Avoid iteration of dying tasks with zero refcount
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux09aa68552d2542cc6c23edd1568ac265dc5d886fVendor (CNA)
Linux Linux0f38453cdb2e17566ccb7c0f3dabd5bd21caca26Vendor (CNA)
Linux Linux429b6f43b4d8c98988fdca99e02dc156134e3d77Vendor (CNA)
Linux Linuxc0a9bd5fca0b5f2dea32b0fc31350e71e8648112Vendor (CNA)
Linux Linuxd8636c8f9f95d0fd1e2f6f1cad0d5757aa6f212aVendor (CNA)
Linux Linuxec8fcaf354c1cbb36755d48e9f5a00c9591349e5Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 9, 2026+41 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6387572 days apartarm64: tlb: Flush walk cache when unsharing PMD tables
    31Monitor
  • CVE-2026-980514 days apartnet: bcmasp: fix tx_spb_ring_full() checking same slot cnt times
    22Monitor
  • CVE-2025-38291446 days apartwifi: ath12k: Prevent sending WMI commands to firmware during firmware crash
    22Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-670 · Always-Incorrect Control Flow Implementation

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

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

  1. CVSS— → 5.5
  2. Severity— → medium
  3. Exploit maturity— → none
  4. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records