Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 s390-vfio-ap status_show null pointer dereference

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.2$0-$5k0.43-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 and classified as critical. Impacted is the function status_show of the component s390-vfio-ap. Executing a manipulation can lead to null pointer dereference. This vulnerability is registered as CVE-2026-89955. It is possible to launch the attack remotely. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

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 critical. This vulnerability affects the function status_show of the component s390-vfio-ap. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: Fix NULL deref in status_show() during queue probe When vfio_ap_mdev_probe_queue() creates the sysfs attribute group, the queue's driver data has not yet been set. A concurrent read of the 'status' attribute can therefore call dev_get_drvdata() and get NULL, which is then passed directly to vfio_ap_mdev_for_queue() where q->apqn is unconditionally dereferenced, causing a NULL pointer dereference. Fix this by acquiring the update locks before calling sysfs_create_group(). The status_show() function acquires guests_lock before reading the driver data, so any concurrent read will block until after dev_set_drvdata() has been called and the update locks are released. As a bonus, the APQN no longer needs to be read from the queue struct after allocation — it can be read directly from apdev before allocation and stored in a local variable, which is then assigned to q->apqn once the allocation succeeds.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-89955 since 09/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/16/2026).

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 31fa0a8a3c337ed2d200166d6926ab23c14f8b2e/e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9/69632952aca04caa71e49953b6949fc04e788e67/7db2511fc601ca3a6e3fb1bdce02261c3c3167c3/dd6f4ef6f8a37412909ad787c837332fb070159c is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
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: Null pointer dereference
CWE: CWE-476 / CWE-404
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: 31fa0a8a3c337ed2d200166d6926ab23c14f8b2e/e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9/69632952aca04caa71e49953b6949fc04e788e67/7db2511fc601ca3a6e3fb1bdce02261c3c3167c3/dd6f4ef6f8a37412909ad787c837332fb070159c

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89955 (🔒)
GCVE (CVE): GCVE-0-2026-89955
GCVE (VulDB): GCVE-100-405850

Entryinfo

Created: 09/16/2026 15:20
Changes: 09/16/2026 15:20 (59)
Complete: 🔍
Cache ID: 216::103

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