CVE-2026-45991: udf: fix partition descriptor append bookkeeping

Q: What access does an attacker need to exploit this issue?

An attacker needs local access and privileges sufficient to cause the system to mount a crafted UDF image. No user interaction is required once the malicious image is mounted.

Q: Which systems are exposed?

Systems using the Linux kernel UDF filesystem handler are exposed when they mount attacker-controlled UDF images. The provided software list also identifies Microsoft azl3 kernel version 6.6.139.1-1.

Q: What happens when the vulnerability is triggered?

A crafted UDF image containing repeated partition descriptors can cause a heap out-of-bounds write in the kernel's partition descriptor location table. The assigned CVSS vector indicates potential high impact to confidentiality, integrity, and availability.

Q: What should be done if the fix cannot be deployed immediately?

Avoid mounting untrusted or attacker-controlled UDF images until the kernel fix is deployed. Restrict which users and processes can mount removable media or disk images that may contain UDF filesystems.

Published May 27, 2026

Updated

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

udf: fix partition descriptor append bookkeeping

Mounting a crafted UDF image with repeated partition descriptors can trigger a heap out-of-bounds write in partdescsloc[].

handlepartitiondescriptor() deduplicates entries by partition number, but appended slots never record partnum. As a result duplicate Partition Descriptors are appended repeatedly and numpartdescs keeps growing.

Once the table is full, the growth path still sizes the allocation from partnum even though inserts are indexed by numpartdescs. If partnum is already aligned to PARTDESCALLOCSTEP, ALIGN(partnum, step) can keep the old capacity and the next append writes past the end of the table.

Store partnum in the appended slot and size growth from the next append count so deduplication and capacity tracking follow the same model.

Affected Software

241 affected componentsFixes available

Linux Linux kernel (udf)

Microsoft azl3 kernel 6.6.139.1-1<6.6.141.1-1

6.6.141.1-1

Linux Linux kernel>=4.18.7<4.19

Linux Linux kernel>=4.19.1<6.6.140

Linux Linux kernel>=6.7<6.12.88

Linux Linux kernel>=6.13<7.0.4

Linux Linux kernel=4.19

Linux Linux kernel=4.19-rc2

Linux Linux kernel=4.19-rc3

Linux Linux kernel=4.19-rc4

Linux Linux kernel=4.19-rc5

Linux Linux kernel=4.19-rc6

Linux Linux kernel=4.19-rc7

Linux Linux kernel=4.19-rc8

F5 F5OS=2.0.0

2.0.0-

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

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-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15<5.15.0-1117.124~20.04.1

5.15.0-1117.124~20.04.1

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

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ubuntu/linux-azure-5.15<5.15.0-1123.132~20.04.1

5.15.0-1123.132~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.15<5.15.0-1122.131~20.04.1

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ubuntu/linux-bluefield*

ubuntu/linux-gcp*

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ubuntu/linux-gcp-5.15<5.15.0-1118.128~20.04.1

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ubuntu/linux-gcp-5.8*

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ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1111.115~20.04.1

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ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1112.118~20.04.1

5.15.0-1112.118~20.04.1

ubuntu/linux-iot*

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ubuntu/linux-nvidia-tegra-5.15*

ubuntu/linux-oem-5.10*

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ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

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ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

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ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<5.15.0-198.208

5.15.0-198.208

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1117.124

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ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

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ubuntu/linux-aws-6.8<6.8.0-1061.64~22.04.1

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ubuntu/linux-azure<5.15.0-1123.132

5.15.0-1123.132

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1063.71~22.04.1

6.8.0-1063.71~22.04.1

ubuntu/linux-azure-fde<5.15.0-1122.131

5.15.0-1122.131

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1062.69~22.04.1

6.8.0-1062.69~22.04.1

ubuntu/linux-gcp<5.15.0-1118.128

5.15.0-1118.128

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1064.72~22.04.1

6.8.0-1064.72~22.04.1

ubuntu/linux-gke<5.15.0-1113.119

5.15.0-1113.119

ubuntu/linux-gkeop<5.15.0-1100.108

5.15.0-1100.108

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-136.136~22.04.1

6.8.0-136.136~22.04.1

ubuntu/linux-ibm<5.15.0-1111.115

5.15.0-1111.115

ubuntu/linux-ibm-6.8<6.8.0-1061.62~22.04.1

6.8.0-1061.62~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1112.118

5.15.0-1112.118

ubuntu/linux-kvm<5.15.0-1109.114

5.15.0-1109.114

ubuntu/linux-lowlatency<5.15.0-195.205

5.15.0-195.205

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-136.136.2~22.04.1

6.8.0-136.136.2~22.04.1

ubuntu/linux-nvidia<5.15.0-1112.113

5.15.0-1112.113

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1059.62~22.04.1

6.8.0-1059.62~22.04.1

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<5.15.0-1114.120

5.15.0-1114.120

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1058.61~22.04.1

6.8.0-1058.61~22.04.1

ubuntu/linux-raspi*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-136.136~22.04.3

6.8.0-136.136~22.04.3

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1080.84

5.15.0-1080.84

ubuntu/linux-bluefield<5.15.0-1101.103

5.15.0-1101.103

ubuntu/linux-intel-iot-realtime<5.15.0-1109.111

5.15.0-1109.111

ubuntu/linux-realtime<5.15.0-1116.125

5.15.0-1116.125

ubuntu/linux-realtime-6.8<6.8.1-1056.57~22.04.2

6.8.1-1056.57~22.04.2

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips<5.15.0-1117.124+fips1

5.15.0-1117.124+fips1

ubuntu/linux-azure-fips<5.15.0-1123.132+fips1

5.15.0-1123.132+fips1

ubuntu/linux-fips<5.15.0-198.208+fips1

5.15.0-198.208+fips1

ubuntu/linux-gcp-fips<5.15.0-1118.128+fips1

5.15.0-1118.128+fips1

ubuntu/linux<6.8.0-136.136

6.8.0-136.136

ubuntu/linux-aws<6.8.0-1061.64

6.8.0-1061.64

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17*

ubuntu/linux-azure<6.8.0-1063.71

6.8.0-1063.71

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17*

ubuntu/linux-azure-fde<6.8.0-1062.69

6.8.0-1062.69

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1064.72

6.8.0-1064.72

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gke<6.8.0-1059.67

6.8.0-1059.67

ubuntu/linux-gkeop<6.8.0-1046.50

6.8.0-1046.50

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17*

ubuntu/linux-hwe-7.0<7.0.0-28.28~24.04.1

7.0.0-28.28~24.04.1

ubuntu/linux-ibm<6.8.0-1061.62

6.8.0-1061.62

ubuntu/linux-lowlatency<6.8.0-136.136.2

6.8.0-136.136.2

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1059.62

6.8.0-1059.62

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-lowlatency<6.8.0-1059.62.1

6.8.0-1059.62.1

ubuntu/linux-nvidia-tegra<6.8.0-1030.31

6.8.0-1030.31

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17*

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1058.61

6.8.0-1058.61

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17*

ubuntu/linux-raspi<6.8.0-1061.65

6.8.0-1061.65

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17*

ubuntu/linux-xilinx<6.8.0-1033.34

6.8.0-1033.34

ubuntu/linux-bluefield<6.8.0-1028.33

6.8.0-1028.33

ubuntu/linux-raspi-realtime<6.8.0-2050.52

6.8.0-2050.52

ubuntu/linux-realtime<6.8.1-1056.57

6.8.1-1056.57

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips<6.8.0-1061.64+fips1

6.8.0-1061.64+fips1

ubuntu/linux-azure-fips<6.8.0-1063.71+fips2

6.8.0-1063.71+fips2

ubuntu/linux-fips<6.8.0-136.136+fips2

6.8.0-136.136+fips2

ubuntu/linux-gcp-fips<6.8.0-1064.72+fips1

6.8.0-1064.72+fips1

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-azure*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp*

ubuntu/linux-oracle*

ubuntu/linux-raspi*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux<7.0.0-27.27

7.0.0-27.27

ubuntu/linux-aws<7.0.0-1008.8

7.0.0-1008.8

ubuntu/linux-azure<7.0.0-1010.10

7.0.0-1010.10

ubuntu/linux-azure-fde<7.0.0-1009.9

7.0.0-1009.9

ubuntu/linux-gcp<7.0.0-1007.7

7.0.0-1007.7

ubuntu/linux-ibm<7.0.0-1009.9

7.0.0-1009.9

ubuntu/linux-nvidia<7.0.0-1013.13

7.0.0-1013.13

ubuntu/linux-oem-7.0<7.0.0-1008.8

7.0.0-1008.8

ubuntu/linux-oracle<7.0.0-1007.7

7.0.0-1007.7

ubuntu/linux-raspi<7.0.0-1014.14

7.0.0-1014.14

ubuntu/linux-realtime<7.0.0-27.27.1

7.0.0-27.27.1

ubuntu/linux-riscv<7.0.0-27.27.1

7.0.0-27.27.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

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Fixed in 7.0.0-1009.9
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Fixed in 7.0.0-1007.7
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Fixed in 7.0.0-1009.9
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Fixed in 7.0.0-1013.13
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Fixed in 7.0.0-1008.8
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Fixed in 7.0.0-1007.7
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Fixed in 7.0.0-1014.14
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Fixed in 7.0.0-27.27.1
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Fixed in 7.0.0-27.27.1

Event History

May 27, 2026

CVE Published

via MITRE·12:55 PM

Data Sourced

via MITRE·12:55 PM

DescriptionSeverity

Data Sourced

via OSV·02:17 PM

DescriptionSeverityAffected Software

Data Sourced

via NVD·02:17 PM

RemedyDescriptionSeverityWeaknessAffected Software

Data Sourced

via Red Hat·03:11 PM

DescriptionSeverityAffected Software

May 28, 2026

Data Sourced

via Microsoft·08:04 AM

DescriptionSeverityWeaknessAffected Software

Oct 5, 2026

Advisory Published

via F5·03:50 PM

Data Sourced

via F5·03:50 PM

DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

What access does an attacker need to exploit this issue?

An attacker needs local access and privileges sufficient to cause the system to mount a crafted UDF image. No user interaction is required once the malicious image is mounted.

Which systems are exposed?

Systems using the Linux kernel UDF filesystem handler are exposed when they mount attacker-controlled UDF images. The provided software list also identifies Microsoft azl3 kernel version 6.6.139.1-1.

What happens when the vulnerability is triggered?

A crafted UDF image containing repeated partition descriptors can cause a heap out-of-bounds write in the kernel's partition descriptor location table. The assigned CVSS vector indicates potential high impact to confidentiality, integrity, and availability.

What should be done if the fix cannot be deployed immediately?

Avoid mounting untrusted or attacker-controlled UDF images until the kernel fix is deployed. Restrict which users and processes can mount removable media or disk images that may contain UDF filesystems.

CVE-2026-45991: udf: fix partition descriptor append bookkeeping

Affected Software

Remediation

Event History

Frequently Asked Questions

What access does an attacker need to exploit this issue?

Which systems are exposed?

What happens when the vulnerability is triggered?

What should be done if the fix cannot be deployed immediately?

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