UBUNTU-CVE-2026-43233: Ubuntu/linux-azure vulnerability

Q: Which systems are exposed to this issue?

Systems using the listed Ubuntu kernel packages are exposed when the nf_conntrack_h323 helper is active and traffic can reach port 1720 through the firewall. The issue is triggered while processing H.323 Q.931 SETUP messages with User-User Information Elements.

Q: What does an attacker need to exploit the vulnerability?

An attacker can trigger it remotely by sending a crafted Q.931 SETUP message containing exactly two bytes of PER-encoded User-User Information data ({0x08, 0x00}) to port 1720. The target firewall must have the nf_conntrack_h323 helper active.

Q: Is a default firewall configuration necessarily affected?

The provided information only identifies systems with the nf_conntrack_h323 helper active as affected. It does not state whether that helper is enabled by default.

Q: What can be done if the kernel cannot be patched immediately?

Prevent untrusted traffic from reaching port 1720 through firewalls where the nf_conntrack_h323 helper is active. Disabling the helper where H.323 connection tracking is not required also removes the stated attack condition.

Published May 6, 2026

Updated

In the Linux kernel, the following vulnerability has been resolved: netfilter: nfconntrackh323: fix OOB read in decodechoice() In decodechoice(), the boundary check before getlen() uses the variable len, which is still 0 from its initialization at the top of the function: unsigned int type, ext, len = 0; ... if (ext || (son->attr & OPEN)) { BYTEALIGN(bs); if (nfh323errorboundary(bs, len, 0)) / len is 0 here / return H323ERRORBOUND; len = getlen(bs); / OOB read / When the bitstream is exactly consumed (bs->cur == bs->end), the check nfh323errorboundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end), which is false. The subsequent getlen() call then dereferences bs->cur++, reading 1 byte past the end of the buffer. If that byte has bit 7 set, getlen() reads a second byte as well. This can be triggered remotely by sending a crafted Q.931 SETUP message with a User-User Information Element containing exactly 2 bytes of PER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with the nfconntrackh323 helper active. The decoder fully consumes the PER buffer before reaching this code path, resulting in a 1-2 byte heap-buffer-overflow read confirmed by AddressSanitizer. Fix this by checking for 2 bytes (the maximum that getlen() may read) instead of the uninitialized len. This matches the pattern used at every other getlen() call site in the same file, where the caller checks for 2 bytes of available data before calling getlen().

Affected Software

233 affected componentsFixes available

ubuntu/linux-azure*

ubuntu/linux-aws-hwe*

ubuntu/linux-azure*

ubuntu/linux-gcp*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-oracle*

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<5.15.0-1112.119~20.04.1

5.15.0-1112.119~20.04.1

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15<5.15.0-1117.126~20.04.1

5.15.0-1117.126~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.15<5.15.0-1117.126~20.04.2

5.15.0-1117.126~20.04.2

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15<5.15.0-1112.122~20.04.1

5.15.0-1112.122~20.04.1

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<5.15.0-186.196~20.04.1

5.15.0-186.196~20.04.1

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1106.110~20.04.1

5.15.0-1106.110~20.04.1

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1107.113~20.04.1

5.15.0-1107.113~20.04.1

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-184.194~20.04.1

5.15.0-184.194~20.04.1

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1064.66~20.04.1

5.15.0-1064.66~20.04.1

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<5.15.0-1109.115~20.04.1

5.15.0-1109.115~20.04.1

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15<5.15.0-1106.110~20.04.1

5.15.0-1106.110~20.04.1

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<5.15.0-186.196

5.15.0-186.196

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1112.119

5.15.0-1112.119

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1060.63~22.04.1

6.8.0-1060.63~22.04.1

ubuntu/linux-azure<5.15.0-1117.126

5.15.0-1117.126

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<5.15.0-1117.126

5.15.0-1117.126

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<5.15.0-1112.122

5.15.0-1112.122

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1063.69~22.04.1

6.8.0-1063.69~22.04.1

ubuntu/linux-gke<5.15.0-1108.114

5.15.0-1108.114

ubuntu/linux-gkeop<5.15.0-1095.103

5.15.0-1095.103

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<5.15.0-1106.110

5.15.0-1106.110

ubuntu/linux-ibm-6.8<6.8.0-1060.61~22.04.1

6.8.0-1060.61~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1107.113

5.15.0-1107.113

ubuntu/linux-kvm<5.15.0-1104.109

5.15.0-1104.109

ubuntu/linux-lowlatency<5.15.0-184.194

5.15.0-184.194

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-134.134.1~22.04.1

6.8.0-134.134.1~22.04.1

ubuntu/linux-nvidia<5.15.0-1107.108

5.15.0-1107.108

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

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

6.8.0-1058.61~22.04.1

ubuntu/linux-nvidia-tegra<5.15.0-1064.66

5.15.0-1064.66

ubuntu/linux-nvidia-tegra-igx<5.15.0-1053.53

5.15.0-1053.53

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1109.115

5.15.0-1109.115

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1057.58~22.04.1

6.8.0-1057.58~22.04.1

ubuntu/linux-raspi<5.15.0-1106.109

5.15.0-1106.109

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-134.134~22.04.1

6.8.0-134.134~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1075.79

5.15.0-1075.79

ubuntu/linux-bluefield<5.15.0-1096.98

5.15.0-1096.98

ubuntu/linux-intel-iot-realtime<5.15.0-1104.106

5.15.0-1104.106

ubuntu/linux-realtime<5.15.0-1111.120

5.15.0-1111.120

ubuntu/linux-realtime-6.8<6.8.1-1055.56~22.04.1

6.8.1-1055.56~22.04.1

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips<5.15.0-1112.119+fips1

5.15.0-1112.119+fips1

ubuntu/linux-azure-fips<5.15.0-1117.126+fips1

5.15.0-1117.126+fips1

ubuntu/linux-fips<5.15.0-186.196+fips1

5.15.0-186.196+fips1

ubuntu/linux-gcp-fips<5.15.0-1112.122+fips1

5.15.0-1112.122+fips1

ubuntu/linux<6.8.0-134.134

6.8.0-134.134

ubuntu/linux-aws<6.8.0-1060.63

6.8.0-1060.63

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<6.8.0-1063.69

6.8.0-1063.69

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gke<6.8.0-1058.64

6.8.0-1058.64

ubuntu/linux-gkeop<6.8.0-1045.48

6.8.0-1045.48

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17*

ubuntu/linux-ibm<6.8.0-1060.61

6.8.0-1060.61

ubuntu/linux-lowlatency<6.8.0-134.134.1

6.8.0-134.134.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1058.61

6.8.0-1058.61

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17*

ubuntu/linux-nvidia-lowlatency<6.8.0-1058.61.1

6.8.0-1058.61.1

ubuntu/linux-nvidia-tegra<6.8.0-1029.30

6.8.0-1029.30

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17*

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1057.58

6.8.0-1057.58

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17*

ubuntu/linux-raspi<6.8.0-1060.64

6.8.0-1060.64

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17*

ubuntu/linux-xilinx<6.8.0-1032.33

6.8.0-1032.33

ubuntu/linux-bluefield<6.8.0-1026.30

6.8.0-1026.30

ubuntu/linux-raspi-realtime<6.8.0-2049.50

6.8.0-2049.50

ubuntu/linux-realtime<6.8.1-1055.56

6.8.1-1055.56

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17*

ubuntu/linux-aws-fips<6.8.0-1060.63+fips1

6.8.0-1060.63+fips1

ubuntu/linux-azure-fips<6.8.0-1062.69+fips1

6.8.0-1062.69+fips1

ubuntu/linux-fips<6.8.0-134.134+fips1

6.8.0-134.134+fips1

ubuntu/linux-gcp-fips<6.8.0-1063.69+fips1

6.8.0-1063.69+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*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.119~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.126~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.126~20.04.2
Upgrade
Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.122~20.04.1
Upgrade
Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-186.196~20.04.1
Upgrade
Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1106.110~20.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1107.113~20.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-184.194~20.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1064.66~20.04.1
Upgrade
Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1109.115~20.04.1
Upgrade
Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1106.110~20.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 5.15.0-186.196
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.119
Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63~22.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.126
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.71~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.126
Upgrade
Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69~22.04.1
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.122
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69~22.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 5.15.0-1108.114
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 5.15.0-1095.103
Upgrade
Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-136.136~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 5.15.0-1106.110
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.61~22.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.
Fixed in 5.15.0-1107.113
Upgrade
Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.
Fixed in 5.15.0-1104.109
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 5.15.0-184.194
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 5.15.0-1107.108
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 5.15.0-1064.66
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-igx to a version that resolves this vulnerability.
Fixed in 5.15.0-1053.53
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 5.15.0-1109.115
Upgrade
Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1057.58~22.04.1
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 5.15.0-1106.109
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134~22.04.1
Upgrade
Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.
Fixed in 5.15.0-1075.79
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 5.15.0-1096.98
Upgrade
Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1104.106
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1111.120
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1055.56~22.04.1
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.119+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1117.126+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-186.196+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1112.122+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.71
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.64
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1045.48
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.61
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 6.8.0-1029.30
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1057.58
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.64
Upgrade
Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.33
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.30
Upgrade
Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.
Fixed in 6.8.0-2049.50
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1055.56
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69+fips1
Compensating control
In nf_conntrack_h323 decode_choice(), check that 2 bytes are available before calling get_len() instead of using the uninitialized len value; get_len() may read a second byte when the first byte has bit 7 set.

Frequently Asked Questions

Which systems are exposed to this issue?

Systems using the listed Ubuntu kernel packages are exposed when the nf_conntrack_h323 helper is active and traffic can reach port 1720 through the firewall. The issue is triggered while processing H.323 Q.931 SETUP messages with User-User Information Elements.

What does an attacker need to exploit the vulnerability?

An attacker can trigger it remotely by sending a crafted Q.931 SETUP message containing exactly two bytes of PER-encoded User-User Information data ({0x08, 0x00}) to port 1720. The target firewall must have the nf_conntrack_h323 helper active.

Is a default firewall configuration necessarily affected?

The provided information only identifies systems with the nf_conntrack_h323 helper active as affected. It does not state whether that helper is enabled by default.

What can be done if the kernel cannot be patched immediately?

Prevent untrusted traffic from reaching port 1720 through firewalls where the nf_conntrack_h323 helper is active. Disabling the helper where H.323 connection tracking is not required also removes the stated attack condition.

UBUNTU-CVE-2026-43233: Ubuntu/linux-azure vulnerability

Affected Software

Remediation

Frequently Asked Questions

Which systems are exposed to this issue?

What does an attacker need to exploit the vulnerability?

Is a default firewall configuration necessarily affected?

What can be done if the kernel cannot be patched immediately?

Company

Resources

Contact

Frequently Asked Questions

Which systems are exposed to this issue?

What does an attacker need to exploit the vulnerability?

Is a default firewall configuration necessarily affected?

What can be done if the kernel cannot be patched immediately?