Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 s390-vfio-ap vfio_ap_mdev_hot_plug_cfg apm_filtered uninitialized resource

CVSS Meta Temp Score
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CTI Interest Score
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9.5$0-$5k0.00

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 and classified as very critical. Impacted is the function vfio_ap_mdev_hot_plug_cfg of the component s390-vfio-ap. This manipulation of the argument apm_filtered causes uninitialized resource. This vulnerability is tracked as CVE-2026-93238. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4. Affected by this vulnerability is the function vfio_ap_mdev_hot_plug_cfg of the component s390-vfio-ap. The manipulation of the argument apm_filtered with an unknown input leads to a uninitialized resource vulnerability. The CWE definition for the vulnerability is CWE-908. The product uses or accesses a resource that has not been initialized. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: fix potential use of uninitialized apm_filtered bitmap The DECLARE_BITMAP(apm_filtered, AP_DEVICES) macro allocates the bitmap on the stack without zero-initializing it. In vfio_ap_mdev_hot_plug_cfg(), the vfio_ap_mdev_filter_matrix() function is only called to initialize and populate apm_filtered if either filter_adapters or filter_domains is true. If the hot plug configuration change only adds control domains (meaning filter_cdoms is true, but filter_adapters and filter_domains are both false), vfio_ap_mdev_filter_matrix() is bypassed. Consequently, apm_filtered is passed to reset_queues_for_apids() with uninitialized stack garbage. This can cause reset_queues_for_apids() to interpret arbitrary stack garbage bits as valid APIDs to reset, potentially performing unintended guest hardware queue resets. Fix this by zero-initializing the apm_filtered bitmap at the beginning of vfio_ap_mdev_hot_plug_cfg() using bitmap_zero().

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-93238 since 09/17/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/24/2026).

Upgrading to version 6.6.157, 6.12.110, 6.18.51, 7.2.5 or 7.3-rc1 eliminates this vulnerability. Applying the patch 4ba8a08f5f26ed59f356a6318bca3aa7cc0af3e2/f73db632524320d2b93bc8534be8ea875053502d/6d554f2571e6b4db242593ba561efd6a6d1f99a9/09548edc6114f1eb1035b30795e893204ef45b85/bf09b9d7cd7890bc3a3b7eb63d5ece15f88bfde7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Uninitialized resource
CWE: CWE-908
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.157/6.12.110/6.18.51/7.2.5/7.3-rc1
Patch: 4ba8a08f5f26ed59f356a6318bca3aa7cc0af3e2/f73db632524320d2b93bc8534be8ea875053502d/6d554f2571e6b4db242593ba561efd6a6d1f99a9/09548edc6114f1eb1035b30795e893204ef45b85/bf09b9d7cd7890bc3a3b7eb63d5ece15f88bfde7

Timelineinfo

09/17/2026 CVE reserved
09/24/2026 +7 days Advisory disclosed
09/24/2026 +0 days VulDB entry created
09/24/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-93238 (🔒)
GCVE (CVE): GCVE-0-2026-93238
GCVE (VulDB): GCVE-100-409447

Entryinfo

Created: 09/24/2026 18:08
Changes: 09/24/2026 18:08 (60)
Complete: 🔍
Cache ID: 216::103

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