CVE-2026-64294: mm: do file ownership checks with the proper mount idmap

Q: What is the severity of CVE-2026-64294?

CVE-2026-64294 has a severity rating of high with a score of 7.1.

Q: How do I fix CVE-2026-64294?

To fix CVE-2026-64294, you should apply the available patches provided for the Linux kernel.

Q: What does CVE-2026-64294 affect?

CVE-2026-64294 affects the Linux kernel, specifically concerning file ownership checks with the proper mount idmap.

Q: When was CVE-2026-64294 published?

CVE-2026-64294 was published on July 25, 2026.

Q: How can CVE-2026-64294 impact system security?

CVE-2026-64294 can potentially lead to unauthorized file access due to improper ownership checks, affecting data integrity and confidentiality.

Published Jul 25, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved:

mm: do file ownership checks with the proper mount idmap

Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADVPAGEOUT) were done against the nopmntidmap, which completely ignores the file's mount's idmap. This results in odd edgecases like:

1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an ownerorcapable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) ownerorcapable() mysteriously fails as the correct idmap wasn't supplied

In the case of mincore/madvise MADVPAGEOUT, this is usually benign, because filepermission(file, MAYWRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it.

Since this is clearly not trivial to get right, introduce a fileownerorcapable() that can carry the correct semantics, and switch the various users in mm to it.

The issue was found by manual code inspection & an off-list discussion with Jan Kara.

Affected Software

208 affected componentsFixes available

Linux Linux kernel

Microsoft azl3 kernel 6.6.144.1-1<6.6.145.2-1

6.6.145.2-1

Linux Linux kernel>=5.12<6.6.145

Linux Linux kernel>=6.7<6.12.96

Linux Linux kernel>=6.13<6.18.39

Linux Linux kernel>=6.19<7.1.4

Linux Linux kernel=7.2-rc1

Linux Linux kernel=7.2-rc2

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15*

ubuntu/linux-aws-5.8*

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-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-5.15*

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15*

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-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.15*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15*

ubuntu/linux-riscv-5.8*

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<6.8.0-147.147

6.8.0-147.147

ubuntu/linux-aws<6.8.0-1067.70

6.8.0-1067.70

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17*

ubuntu/linux-aws-7.0<7.0.0-1012.12~24.04.1

7.0.0-1012.12~24.04.1

ubuntu/linux-azure<6.8.0-1071.79

6.8.0-1071.79

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17*

ubuntu/linux-azure-7.0<7.0.0-1014.14~24.04.1

7.0.0-1014.14~24.04.1

ubuntu/linux-azure-fde<6.8.0-1069.76

6.8.0-1069.76

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-fde-6.17*

ubuntu/linux-azure-fde-7.0<7.0.0-1013.13~24.04.1

7.0.0-1013.13~24.04.1

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1071.79

6.8.0-1071.79

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-7.0<7.0.0-1011.11~24.04.1

7.0.0-1011.11~24.04.1

ubuntu/linux-gke<6.8.0-1066.74

6.8.0-1066.74

ubuntu/linux-gkeop<6.8.0-1052.56

6.8.0-1052.56

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17*

ubuntu/linux-hwe-7.0<7.0.0-31.31~24.04.1

7.0.0-31.31~24.04.1

ubuntu/linux-ibm<6.8.0-1067.68

6.8.0-1067.68

ubuntu/linux-lowlatency<6.8.0-147.147.1

6.8.0-147.147.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia*

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-7.0<7.0.0-1018.18~24.04.1

7.0.0-1018.18~24.04.1

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<6.8.0-1064.67

6.8.0-1064.67

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17*

ubuntu/linux-oracle-7.0<7.0.0-1011.11~24.04.1

7.0.0-1011.11~24.04.1

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<7.0.0-31.31.1~24.04.1

7.0.0-31.31.1~24.04.1

ubuntu/linux-xilinx*

ubuntu/linux-bluefield<6.8.0-1033.38

6.8.0-1033.38

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime<6.8.1-1062.63

6.8.1-1062.63

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips<6.8.0-1067.70+fips1

6.8.0-1067.70+fips1

ubuntu/linux-azure-fips<6.8.0-1071.79+fips1

6.8.0-1071.79+fips1

ubuntu/linux-fips<6.8.0-147.147+fips1

6.8.0-147.147+fips1

ubuntu/linux-gcp-fips<6.8.0-1071.79+fips1

6.8.0-1071.79+fips1

ubuntu/linux<7.0.0-31.31

7.0.0-31.31

ubuntu/linux-aws<7.0.0-1012.12

7.0.0-1012.12

ubuntu/linux-azure<7.0.0-1014.14

7.0.0-1014.14

ubuntu/linux-azure-fde<7.0.0-1013.13

7.0.0-1013.13

ubuntu/linux-gcp<7.0.0-1011.11

7.0.0-1011.11

ubuntu/linux-gke<7.0.0-1006.7

7.0.0-1006.7

ubuntu/linux-ibm<7.0.0-1013.13

7.0.0-1013.13

ubuntu/linux-nvidia<7.0.0-1018.18

7.0.0-1018.18

ubuntu/linux-nvidia-bos<7.0.0-2018.18

7.0.0-2018.18

ubuntu/linux-oem-7.0<7.0.0-1013.13

7.0.0-1013.13

ubuntu/linux-oracle<7.0.0-1011.11

7.0.0-1011.11

ubuntu/linux-raspi<7.0.0-1019.19

7.0.0-1019.19

ubuntu/linux-realtime<7.0.0-31.31.1

7.0.0-31.31.1

ubuntu/linux-riscv<7.0.0-31.31.1

7.0.0-31.31.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.6.145.2-1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.70
Upgrade
Upgrade ubuntu/linux-aws-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1012.12~24.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79
Upgrade
Upgrade ubuntu/linux-azure-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 6.8.0-1069.76
Upgrade
Upgrade ubuntu/linux-azure-fde-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13~24.04.1
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79
Upgrade
Upgrade ubuntu/linux-gcp-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1011.11~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.74
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1052.56
Upgrade
Upgrade ubuntu/linux-hwe-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-31.31~24.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.68
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147.1
Upgrade
Upgrade ubuntu/linux-nvidia-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1018.18~24.04.1
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1064.67
Upgrade
Upgrade ubuntu/linux-oracle-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1011.11~24.04.1
Upgrade
Upgrade ubuntu/linux-riscv-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-31.31.1~24.04.1
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1033.38
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1062.63
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1067.70+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-147.147+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1071.79+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 7.0.0-31.31
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 7.0.0-1012.12
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 7.0.0-1014.14
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 7.0.0-1011.11
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 7.0.0-1006.7
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 7.0.0-1018.18
Upgrade
Upgrade ubuntu/linux-nvidia-bos to a version that resolves this vulnerability.
Fixed in 7.0.0-2018.18
Upgrade
Upgrade ubuntu/linux-oem-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1013.13
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 7.0.0-1011.11
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 7.0.0-1019.19
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 7.0.0-31.31.1
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 7.0.0-31.31.1

Event History

Jul 25, 2026

CVE Published

via MITRE·08:49 AM

Data Sourced

via MITRE·08:49 AM

Description

Data Sourced

via OSV·10:17 AM

DescriptionSeverityAffected Software

Data Sourced

via NVD·10:17 AM

RemedyDescriptionSeverityAffected Software

Jul 26, 2026

Data Sourced

via Microsoft·08:01 AM

DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

What is the severity of CVE-2026-64294?

CVE-2026-64294 has a severity rating of high with a score of 7.1.

How do I fix CVE-2026-64294?

To fix CVE-2026-64294, you should apply the available patches provided for the Linux kernel.

What does CVE-2026-64294 affect?

CVE-2026-64294 affects the Linux kernel, specifically concerning file ownership checks with the proper mount idmap.

When was CVE-2026-64294 published?

CVE-2026-64294 was published on July 25, 2026.

How can CVE-2026-64294 impact system security?

CVE-2026-64294 can potentially lead to unauthorized file access due to improper ownership checks, affecting data integrity and confidentiality.

CVE-2026-64294: mm: do file ownership checks with the proper mount idmap

Affected Software

Remediation

Event History

Frequently Asked Questions

What is the severity of CVE-2026-64294?

How do I fix CVE-2026-64294?

What does CVE-2026-64294 affect?

When was CVE-2026-64294 published?

How can CVE-2026-64294 impact system security?

Company

Resources

Contact