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Vulnerability · Published Jun 26, 2026 · Assigned by Linux

CVE-2026-53306tty: hvc_iucv: fix off-by-one in number of supported devices

Medium 5.5

In plain English

A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.2%top 94.5% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: tty: hvc_iucv: fix off-by-one in number of supported devices MAX_HVC_IUCV_LINES == HVC_ALLOC_TTY_ADAPTERS == 8. This is the number of entries in: static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES]; Sometimes hvc_iucv_table[] is limited by: (a) if (num > hvc_iucv_devices) // for error detection or (b) for (i = 0; i < hvc_iucv_devices; i++) // in 2 places (so these 2 don't agree; second one appears to be correct to me.) hvc_iucv_devices can be 0..8. This is a counter. (c) if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) If hvc_iucv_devices == 8, (a) allows the code to access hvc_iucv_table[8]. Oops.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.176-1DEBIAN-CVE-2026-53306
Debian:13linux6.12.94-1DEBIAN-CVE-2026-53306
Debian:14linux7.0.10-1DEBIAN-CVE-2026-53306
Ubuntu:22.04:LTSlinux5.15.0-186.196UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux6.8.0-136.136UBUNTU-CVE-2026-53306
Ubuntu:25.10linuxno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux7.0.0-28.28UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-aws5.15.0-1112.119UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-aws6.8.0-1061.64UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-awsno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-aws7.0.0-1009.9UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1061.64~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure5.15.0-1117.126UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure6.8.0-1063.71UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-azure7.0.0-1010.10UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1063.71~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1117.126UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1062.69UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1009.9UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1062.69~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gcp5.15.0-1112.122UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gcp6.8.0-1064.72UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-gcpno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-gcp7.0.0-1008.8UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1064.72~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gke5.15.0-1108.114UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gke6.8.0-1059.67UBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-gke7.0.0-1003.4UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1095.103UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1046.50UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-136.136~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-28.28~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-ibm5.15.0-1106.110UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-ibm6.8.0-1061.62UBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-ibm7.0.0-1010.10UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1061.62~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1107.113UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-kvm5.15.0-1104.109UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-184.194UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-136.136.2UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-136.136.2~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1107.108UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1059.62UBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-nvidia7.0.0-1016.16UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1059.62~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1016.16~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2016.16UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1059.62.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1064.66UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1030.31UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1053.53UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1009.9UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oracle5.15.0-1109.115UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oracle6.8.0-1058.61UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-oracleno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-oracle7.0.0-1008.8UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1058.61~22.04.1UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-raspi5.15.0-1106.109UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-raspi6.8.0-1061.65UBUNTU-CVE-2026-53306
Ubuntu:25.10linux-raspino fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-raspi7.0.0-1015.15UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:25.10linux-realtimeno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-realtime7.0.0-28.28.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-53306
Ubuntu:25.10linux-riscvno fix listedUBUNTU-CVE-2026-53306
Ubuntu:26.04:LTSlinux-riscv7.0.0-28.28.1UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-136.136~22.04.3UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-28.28.1~24.04.3UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-53306
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1033.34UBUNTU-CVE-2026-53306
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1075.79UBUNTU-CVE-2026-53306

Affected products (as reported)

VendorProductVersions
Linux Linux 44a01d5ba8a4d543694461cd3e178cfa6b3f221b – before 3d3b89e6ab93bdd0efd45828bda6b0e61cc46dff44a01d5ba8a4d543694461cd3e178cfa6b3f221b – before 484357dff256c816d9466bda35eb765685e4dc8644a01d5ba8a4d543694461cd3e178cfa6b3f221b – before 11207e42a332eb8bbcb9fe74df9edd2a807c560744a01d5ba8a4d543694461cd3e178cfa6b3f221b – before fed8b8f33a46db0ee2efdb000f4f630c86ed8ca444a01d5ba8a4d543694461cd3e178cfa6b3f221b – before a76511bc654819425d3b15e77b523d7f9d81f06444a01d5ba8a4d543694461cd3e178cfa6b3f221b – before 3104a3f40feb107f77d7116ad9bf6c210ab7babf44a01d5ba8a4d543694461cd3e178cfa6b3f221b – before f1dc8e72de9aabe5d96767a4e97219ac26b79fe544a01d5ba8a4d543694461cd3e178cfa6b3f221b – before f2a880e802ad12d1e38039d1334fb1475d0f5241
Linux Linux 2.6.29

References