UBUNTU-CVE-2026-97564: High severity ubuntu/linux vulnerability

Q: Who can exploit this issue?

A local attacker who can create or request cifs.idmap keys and supply a non-NULL callout to request_key(2) can reach the vulnerable path. The issue is local-only and requires low privileges; no user interaction is required.

Q: What is the security impact?

Unvetted authority-bearing fields in a userspace-created cifs.idmap key description can be consumed by the cifs.idmap helper through a root usermodehelper upcall. This can result in high impacts to confidentiality, integrity, and availability within the vulnerable system.

Q: Are normal kernel CIFS ID mapping operations affected by the restriction?

The intended kernel-originated ID mapping paths are unaffected. The fix continues to allow descriptions requested while CIFS uses its private root credentials, including the id_to_sid() and sid_to_id() paths.

Q: How can I determine whether a system needs attention?

Systems using the listed Ubuntu Linux kernel packages should be evaluated for this CVE, particularly where untrusted local users can run request_key(2) or add_key(2). The affected component is the kernel CIFS client cifs.idmap key handling.

Published Sep 25, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject userspace cifs.idmap descriptions cifs.idmap key descriptions carry authority-bearing fields (owner and group SIDs and uid/gid values in "os:"/"gs:"/"oi:"/"gi:" form) that the cifs.idmap upcall helper treats as kernel-originating inputs. Unlike its sibling cifs.spnego, the cifs.idmap key type has no vetdescription hook, so userspace can create keys of this type through requestkey(2)/addkey(2) and supply those fields without CIFS origin. A requestkey(2) call with a non-NULL callout then drives a root usermodehelper upcall (/sbin/request-key -> cifs.idmap) that consumes the unvetted description in root context. Only accept cifs.idmap descriptions while CIFS is using its private rootcred to request the key. idtosid()/sidtoid() already run under overridecreds(rootcred), so the kernel-originated path is unaffected. This mirrors commit 3da1fdf4efbc ("smb: client: reject userspace cifs.spnego descriptions"), which applied the same restriction to cifs.spnego.

Affected Software

254 affected componentsFixes available

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-azure*

ubuntu/linux-lts-xenial*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-hwe*

ubuntu/linux-azure*

ubuntu/linux-gcp*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-kvm*

ubuntu/linux-oracle*

ubuntu/linux-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4*

ubuntu/linux-azure*

ubuntu/linux-azure-4.15*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-4.15*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4*

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4*

ubuntu/linux-kvm*

ubuntu/linux-oem*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15*

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.15*

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15*

ubuntu/linux-gcp-5.8*

ubuntu/linux-gke*

ubuntu/linux-gke-5.15*

ubuntu/linux-gkeop*

ubuntu/linux-gkeop-5.15*

ubuntu/linux-hwe-5.11*

ubuntu/linux-hwe-5.13*

ubuntu/linux-hwe-5.15*

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15*

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15*

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15*

ubuntu/linux-nvidia-tegra-5.15*

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.15*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15*

ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws*

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8*

ubuntu/linux-gke*

ubuntu/linux-gkeop*

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-ibm*

ubuntu/linux-ibm-6.8*

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency*

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8*

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8*

ubuntu/linux-nvidia-tegra*

ubuntu/linux-nvidia-tegra-igx*

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle*

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8*

ubuntu/linux-raspi*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8*

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-bluefield*

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-realtime*

ubuntu/linux-realtime-6.8*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17*

ubuntu/linux-aws-7.0*

ubuntu/linux-azure*

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17*

ubuntu/linux-azure-7.0*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-fde-6.17*

ubuntu/linux-azure-fde-7.0*

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp*

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-7.0*

ubuntu/linux-gke*

ubuntu/linux-gkeop*

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17*

ubuntu/linux-hwe-7.0<7.0.0-42.42~24.04.1

7.0.0-42.42~24.04.1

ubuntu/linux-ibm*

ubuntu/linux-lowlatency*

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-7.0*

ubuntu/linux-nvidia-lowlatency*

ubuntu/linux-nvidia-tegra*

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17*

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle*

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17*

ubuntu/linux-oracle-7.0*

ubuntu/linux-raspi*

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17*

ubuntu/linux-riscv-7.0<7.0.0-42.42.1~24.04.1

7.0.0-42.42.1~24.04.1

ubuntu/linux-xilinx*

ubuntu/linux-bluefield*

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<7.0.0-42.42

7.0.0-42.42

ubuntu/linux-aws<7.0.0-1016.17

7.0.0-1016.17

ubuntu/linux-azure*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp<7.0.0-1016.18

7.0.0-1016.18

ubuntu/linux-gke*

ubuntu/linux-ibm<7.0.0-1017.17

7.0.0-1017.17

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-bos*

ubuntu/linux-oem-7.0<7.0.0-1017.17

7.0.0-1017.17

ubuntu/linux-oracle<7.0.0-1015.16

7.0.0-1015.16

ubuntu/linux-raspi*

ubuntu/linux-realtime*

ubuntu/linux-riscv<7.0.0-42.42.1

7.0.0-42.42.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-hwe-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-42.42~24.04.1
Upgrade
Upgrade ubuntu/linux-riscv-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-42.42.1~24.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 7.0.0-42.42
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.17
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.18
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 7.0.0-1017.17
Upgrade
Upgrade ubuntu/linux-oem-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1017.17
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 7.0.0-1015.16
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 7.0.0-42.42.1
Compensating control
For cifs.idmap key descriptions, accept userspace descriptions only while CIFS is using its private root_cred to request the key.

Event History

Sep 25, 2026

CVE Published

via OSV·11:17 AM

Data Sourced

via OSV·11:17 AM

DescriptionSeverityAffected Software

Frequently Asked Questions

Who can exploit this issue?

A local attacker who can create or request cifs.idmap keys and supply a non-NULL callout to request_key(2) can reach the vulnerable path. The issue is local-only and requires low privileges; no user interaction is required.

What is the security impact?

Unvetted authority-bearing fields in a userspace-created cifs.idmap key description can be consumed by the cifs.idmap helper through a root usermodehelper upcall. This can result in high impacts to confidentiality, integrity, and availability within the vulnerable system.

Are normal kernel CIFS ID mapping operations affected by the restriction?

The intended kernel-originated ID mapping paths are unaffected. The fix continues to allow descriptions requested while CIFS uses its private root credentials, including the id_to_sid() and sid_to_id() paths.

How can I determine whether a system needs attention?

Systems using the listed Ubuntu Linux kernel packages should be evaluated for this CVE, particularly where untrusted local users can run request_key(2) or add_key(2). The affected component is the kernel CIFS client cifs.idmap key handling.

UBUNTU-CVE-2026-97564: High severity ubuntu/linux vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

Who can exploit this issue?

What is the security impact?

Are normal kernel CIFS ID mapping operations affected by the restriction?

How can I determine whether a system needs attention?

Company

Resources

Contact

Frequently Asked Questions

Who can exploit this issue?

What is the security impact?

Are normal kernel CIFS ID mapping operations affected by the restriction?

How can I determine whether a system needs attention?