UBUNTU-CVE-2026-63949: Medium severity ubuntu/linux-hwe-edge vulnerability

Q: What access is needed to trigger the userspace-reachable path?

An attacker needs the ability to perform a zero-byte write to the line-display message sysfs attribute. That attribute is exposed through the message_store() callback and has mode 0644.

Q: What happens when the issue is triggered?

On a KASAN-enabled kernel, the out-of-bounds read can produce a KASAN report and panic. On stock kernels, it silently reads adjacent slab data; if that byte is a newline, the length can wrap from zero to -1 before being passed to kmemdup_nul().

Q: Which Ubuntu kernel packages are listed for this CVE?

The listed packages are ubuntu/linux-riscv, ubuntu/linux-realtime, ubuntu/linux-azure, ubuntu/linux-gcp, ubuntu/linux-azure-fde, ubuntu/linux-gke, ubuntu/linux-hwe-edge, and ubuntu/linux-gkeop.

Published Jul 20, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved: auxdisplay: line-display: fix OOB read on zero-length messagestore() linedispdisplay() unconditionally reads msg[count - 1] before checking whether count is zero, so a write of zero bytes to the message sysfs attribute hits msg[-1]: write(fd, "", 0); -> messagestore(..., buf, count=0) -> linedispdisplay(linedisp, buf, count=0) -> msg[count - 1] == '\n' ; OOB read The kernfs write buffer for that store is a 1-byte allocation (kernfsfopwriteiter() does kmalloc(len + 1) with len == 0), so msg[-1] is a 1-byte read before the slab object. On a KASAN-enabled kernel this trips an out-of-bounds report and panics; on stock kernels it silently reads adjacent slab data and, if that byte happens to be '\n', the following count-- wraps ssizet 0 to -1 and is then passed to kmemdupnul(). linedispdisplay() is reached from the messagestore() sysfs callback (drivers/auxdisplay/line-display.c message attribute, mode 0644) and from the in-tree initial-message setup with count == -1, so the OOB path is only userspace-triggerable via zero-byte writes; vfswrite() does not short-circuit on count == 0 and kernfsfopwriteiter() dispatches the store callback regardless. Guard the trailing-newline trim with a count check. The existing if (!count) block then takes the clear-display path unchanged. Affects every auxdisplay driver that registers via linedispregister() / linedispattach(): ht16k33, max6959, img-ascii-lcd, seg-led-gpio.

Affected Software

160 affected componentsFixes available

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-5.8*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

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-5.8*

ubuntu/linux-intel-5.13*

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-5.8*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.8*

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1066.69~22.04.1

6.8.0-1066.69~22.04.1

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1070.78~22.04.1

6.8.0-1070.78~22.04.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1068.75~22.04.1

6.8.0-1068.75~22.04.1

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1070.78~22.04.1

6.8.0-1070.78~22.04.1

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-ibm-6.8<6.8.0-1066.67~22.04.1

6.8.0-1066.67~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-146.146.1~22.04.1

6.8.0-146.146.1~22.04.1

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1064.67~22.04.1

6.8.0-1064.67~22.04.1

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-146.146~22.04.1

6.8.0-146.146~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-realtime-6.8<6.8.1-1061.62~22.04.1

6.8.1-1061.62~22.04.1

ubuntu/linux<6.8.0-146.146

6.8.0-146.146

ubuntu/linux-aws<6.8.0-1066.69

6.8.0-1066.69

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17*

ubuntu/linux-azure<6.8.0-1070.78

6.8.0-1070.78

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<6.8.0-1068.75

6.8.0-1068.75

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<6.8.0-1070.78

6.8.0-1070.78

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<6.8.0-1065.73

6.8.0-1065.73

ubuntu/linux-gkeop<6.8.0-1051.55

6.8.0-1051.55

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<6.8.0-1066.67

6.8.0-1066.67

ubuntu/linux-lowlatency<6.8.0-146.146.1

6.8.0-146.146.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1064.67

6.8.0-1064.67

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-7.0<7.0.0-1016.16~24.04.1

7.0.0-1016.16~24.04.1

ubuntu/linux-nvidia-lowlatency<6.8.0-1064.67.1

6.8.0-1064.67.1

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<6.8.0-1063.66

6.8.0-1063.66

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<7.0.0-28.28.1~24.04.3

7.0.0-28.28.1~24.04.3

ubuntu/linux-xilinx*

ubuntu/linux-bluefield<6.8.0-1032.37

6.8.0-1032.37

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime<6.8.1-1061.62

6.8.1-1061.62

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips<6.8.0-1066.69+fips1

6.8.0-1066.69+fips1

ubuntu/linux-azure-fips<6.8.0-1069.77+fips1

6.8.0-1069.77+fips1

ubuntu/linux-fips<6.8.0-146.146+fips1

6.8.0-146.146+fips1

ubuntu/linux-gcp-fips<6.8.0-1070.78+fips1

6.8.0-1070.78+fips1

ubuntu/linux<7.0.0-28.28

7.0.0-28.28

ubuntu/linux-aws<7.0.0-1009.9

7.0.0-1009.9

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<7.0.0-1008.8

7.0.0-1008.8

ubuntu/linux-gke<7.0.0-1003.4

7.0.0-1003.4

ubuntu/linux-ibm<7.0.0-1010.10

7.0.0-1010.10

ubuntu/linux-nvidia<7.0.0-1016.16

7.0.0-1016.16

ubuntu/linux-nvidia-bos<7.0.0-2016.16

7.0.0-2016.16

ubuntu/linux-oem-7.0<7.0.0-1009.9

7.0.0-1009.9

ubuntu/linux-oracle<7.0.0-1008.8

7.0.0-1008.8

ubuntu/linux-raspi<7.0.0-1015.15

7.0.0-1015.15

ubuntu/linux-realtime<7.0.0-28.28.1

7.0.0-28.28.1

ubuntu/linux-riscv<7.0.0-28.28.1

7.0.0-28.28.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.69~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1070.78~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1068.75~22.04.1
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1070.78~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.67~22.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-146.146.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1064.67~22.04.1
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-146.146~22.04.1
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1061.62~22.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-146.146
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.69
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1070.78
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 6.8.0-1068.75
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 6.8.0-1070.78
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 6.8.0-1065.73
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1051.55
Upgrade
Upgrade ubuntu/linux-hwe-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-28.28~24.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.67
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-146.146.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1064.67
Upgrade
Upgrade ubuntu/linux-nvidia-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.16~24.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1064.67.1
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.66
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 7.0.0-28.28.1~24.04.3
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.37
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1061.62
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1066.69+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1069.77+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-146.146+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1070.78+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 7.0.0-28.28
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 7.0.0-1009.9
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 7.0.0-1010.10
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 7.0.0-1009.9
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 7.0.0-1008.8
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 7.0.0-1003.4
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 7.0.0-1010.10
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 7.0.0-1016.16
Upgrade
Upgrade ubuntu/linux-nvidia-bos to a version that resolves this vulnerability.
Fixed in 7.0.0-2016.16
Upgrade
Upgrade ubuntu/linux-oem-7.0 to a version that resolves this vulnerability.
Fixed in 7.0.0-1009.9
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 7.0.0-1008.8
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 7.0.0-1015.15
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 7.0.0-28.28.1
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 7.0.0-28.28.1
Compensating control
In linedisp_display(), check that count is nonzero before reading msg[count - 1] or trimming a trailing newline; apply this fix to auxdisplay drivers registering via linedisp_register() or linedisp_attach(), including ht16k33, max6959, img-ascii-lcd, and seg-led-gpio.

Event History

Jul 20, 2026

CVE Published

via OSV·12:00 AM

Data Sourced

via OSV·12:00 AM

DescriptionSeverityAffected Software

Frequently Asked Questions

What access is needed to trigger the userspace-reachable path?

An attacker needs the ability to perform a zero-byte write to the line-display message sysfs attribute. That attribute is exposed through the message_store() callback and has mode 0644.

What happens when the issue is triggered?

On a KASAN-enabled kernel, the out-of-bounds read can produce a KASAN report and panic. On stock kernels, it silently reads adjacent slab data; if that byte is a newline, the length can wrap from zero to -1 before being passed to kmemdup_nul().

Which Ubuntu kernel packages are listed for this CVE?

The listed packages are ubuntu/linux-riscv, ubuntu/linux-realtime, ubuntu/linux-azure, ubuntu/linux-gcp, ubuntu/linux-azure-fde, ubuntu/linux-gke, ubuntu/linux-hwe-edge, and ubuntu/linux-gkeop.

UBUNTU-CVE-2026-63949: Medium severity ubuntu/linux-hwe-edge vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

What access is needed to trigger the userspace-reachable path?

What happens when the issue is triggered?

Which Ubuntu kernel packages are listed for this CVE?

Company

Resources

Contact

Frequently Asked Questions

What access is needed to trigger the userspace-reachable path?

What happens when the issue is triggered?

Which Ubuntu kernel packages are listed for this CVE?