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Vulnerability · Published Apr 1, 2026 · Assigned by Linux

CVE-2026-23405apparmor: fix: limit the number of levels of policy namespaces

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 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.2%top 92.0% 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: apparmor: fix: limit the number of levels of policy namespaces Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it is possible to create them and nest them arbitrarily deep which can be used to exhaust system resource. Hard cap policy namespaces to the same depth as user namespaces.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.164-1DEBIAN-CVE-2026-23405
Debian:13linux6.12.74-2DEBIAN-CVE-2026-23405
Debian:14linux6.19.6-2DEBIAN-CVE-2026-23405
Ubuntu:22.04:LTSlinux5.15.0-173.183UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux6.8.0-106.106UBUNTU-CVE-2026-23405
Ubuntu:25.10linux6.17.0-19.19UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-aws5.15.0-1103.110UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-aws6.8.0-1050.53UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-aws6.17.0-1009.9UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1009.9~24.04.2UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1050.53~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure5.15.0-1109.118UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure6.8.0-1051.57UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-azure6.17.0-1010.10UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1010.10~24.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1051.57~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1109.118.1UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1058.65UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1058.65~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gcp5.15.0-1103.112UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gcp6.8.0-1052.55UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-gcp6.17.0-1009.9UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1009.9~24.04.3UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1052.55~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gke5.15.0-1099.105UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gke6.8.0-1048.53UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1086.94UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1035.38UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-19.19~24.04.2UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-106.106~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-ibm5.15.0-1097.100UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-ibm6.8.0-1049.49UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1049.49~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1098.104UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-kvm5.15.0-1095.100UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-173.183UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-106.106.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-106.106.1~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1098.99UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1049.52UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1014.14UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1049.52~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1049.52.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1055.55UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1020.20UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1044.44UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1017.17UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oracle5.15.0-1100.106UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oracle6.8.0-1047.48UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-oracle6.17.0-1009.9UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1009.9~24.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1047.48~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-raspi5.15.0-1097.100UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-raspi6.8.0-1050.54UBUNTU-CVE-2026-23405
Ubuntu:25.10linux-raspi6.17.0-1010.10UBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-23405
Ubuntu:25.10linux-realtime6.17.0-1008.9UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-23405
Ubuntu:25.10linux-riscv6.17.0-19.19.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-riscv-6.176.17.0-19.19.1~24.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-106.106~22.04.1UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-23405
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1028.29UBUNTU-CVE-2026-23405
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1067.71UBUNTU-CVE-2026-23405

Affected products (as reported)

VendorProductVersions
Linux Linux c88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 6b396cc2f0365e684fc1d3547d18ef79fcee225dc88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 87d0cecc900e55d55fc4dbfb43ac93e269c7a5b3c88d4c7b049e87998ac0a9f455aa545cc895ef92 – before b1226e37eb3754d389721c135db6107db94c7a72c88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 3f8699b3ee0c04b4b9bc27b82cd89a40e81e1d2ec88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 853ce31ca72097d23991a06876a2ccb5cb64b603c88d4c7b049e87998ac0a9f455aa545cc895ef92 – before d42b2b6bb77ca40ee34ab74ad79305840b5f315dc88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 7b6495ead2c611647f6b11441a852324e3eb8616c88d4c7b049e87998ac0a9f455aa545cc895ef92 – before 306039414932c80f8420695a24d4fe10c84ccfb2
Linux Linux 2.6.36

References