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NVD / CVE Program· CNA Linux

CVE-2026-89957: s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.16% (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 04b35dd88c108b2d2ceaaa396aba1cb4049d5831, 3a9b049bbdc40165d7f3e20b818eec95e5694d96, 753aa3bb1273bc0d36adb013d5915cc8ff6b72a9.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 04b35dd88c108b2d2ceaaa396aba1cb4049d5831, 3a9b049bbdc40165d7f3e20b818eec95e5694d96, 753aa3bb1273bc0d36adb013d5915cc8ff6b72a9 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: s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed The vfio_ap_mdev_hot_unplug_cfg() function uses the return value of bitmap_andnot() to determine whether the guest APCB needs to be updated. However, bitmap_andnot() returns false when the resulting destination bitmap is empty. This means that if the only adapter, domain or control domain assigned to an mdev is removed from the host's AP configuration, the bit is correctly cleared from the shadow APCB, but bitmap_andnot() returns false because the result is an empty bitmap. Consequently, do_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called, leaving the KVM guest with stale hardware access to the unplugged AP devices. Fix this by replacing the bitmap_andnot() return value check with bitmap_intersects() to determine whether the shadow APCB actually overlaps with the removal mask. If there is an intersection, call bitmap_andnot() solely for its side effect of clearing the bits, then unconditionally set do_hotplug to trigger the guest APCB update.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Sep 16, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
8.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • No public exploit code on record
  • A fix has been released

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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.

—

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

    • 6.0affected
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before f58e824de8577fe411f6199d659731a0f86a7275affected · git
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before 3a9b049bbdc40165d7f3e20b818eec95e5694d96affected · git
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before 753aa3bb1273bc0d36adb013d5915cc8ff6b72a9affected · git
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before c45753c32d452d10d8efaeb52587e9e6e8126e33affected · git
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before 04b35dd88c108b2d2ceaaa396aba1cb4049d5831affected · git
    • eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 and later · before 917f509bfb88048094dbb85c4e9dbc4d6fe4a886affected · git
    • before 6.0not affected · semver
    • 6.1.188 and later · up to and including 6.1.*not affected · semver
    • 6.6.157 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 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89955Sep 16, 2026 · s390/vfio-ap: Fix NULL deref in status_show() during queue probe
    0Monitor
  • ← EarlierCVE-2026-89956Sep 16, 2026 · s390/vfio-ap: Fix missing lock required to access list of ap_matrix_mdev objects
    0Monitor
  • Later →CVE-2026-89958Sep 16, 2026 · s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL
    0Monitor

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 Linux04b35dd88c108b2d2ceaaa396aba1cb4049d5831Vendor (CNA)
Linux Linux3a9b049bbdc40165d7f3e20b818eec95e5694d96Vendor (CNA)
Linux Linux753aa3bb1273bc0d36adb013d5915cc8ff6b72a9Vendor (CNA)
Linux Linux917f509bfb88048094dbb85c4e9dbc4d6fe4a886Vendor (CNA)
Linux Linuxc45753c32d452d10d8efaeb52587e9e6e8126e33Vendor (CNA)
Linux Linuxf58e824de8577fe411f6199d659731a0f86a7275Vendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package 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.

No dated events beyond publication.

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.

No nightly-computed relations.

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

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. 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