CriticalCVE-2022-0492

    Linux Kernel Improper Authentication Vulnerability (CVE-2022-0492)

    Published In CISA KEV since Sources: BSI, OSV, SingCERT, Debian, CVE.org

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    What is affected, what to do

    A vulnerability was found in the Linux kernel’s cgroup_release_agent_write in the kernel/cgroup/cgroup-v1.c function. This flaw, under certain circumstances, allows the use of the cgroups v1 release_agent feature to escalate privileges and bypass the namespace isolation unexpectedly.

    The vulnerability is being actively exploited; treat it as a priority. Update APM Edge to version v6.3, :linux_kernel: to version :2022-06-05. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Kernel eq kernel 5.17 rc3..kernel 5.17 rc3

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: BSI, OSV, SingCERT, Debian, CVE.org

    5.5 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 92.9

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    208.44 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    5.5 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    92.9
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 2 June 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-287

    Response and mitigation

    Why act now?

    Prioritisation rationale

    Exploitation needs local, low-privileged access, but the real risk is in containerised environments. There the flaw breaks namespace isolation and turns code execution inside a container into root on the host, making it a textbook second stage after a web-app or supply-chain foothold. Its exploitation likelihood ranks well above most CVEs, and public exploit code has been available for a long time. CISA does not flag known ransomware use. Treat it as top priority if you run Kubernetes, shared CI runners or privileged containers on older Ubuntu/Debian kernels. Standalone servers without containers and with AppArmor/SELinux and seccomp active can follow the regular patch cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the kernel update: The fix in cgroup_release_agent_write (kernel/cgroup/cgroup-v1.c) requires CAP_SYS_ADMIN in the initial user namespace. Patches are available from the distributions (Canonical for Ubuntu 14.04/16.04/18.04/20.04/22.04, Debian 9/10). Look up the exact package version in the relevant vendor advisory (USN/DSA). Reboot afterwards unless Livepatch demonstrably covers this fix, and verify with uname -r.
      • Patch container hosts first: Start with Kubernetes nodes, Docker/Podman hosts, CI/CD runners (GitLab, Jenkins) and multi-tenant systems that run untrusted code. On these hosts the bug becomes a container-to-host escape.
      • Inventory privileged containers: Find workloads with privileged: true, CAP_SYS_ADMIN, seccomp=unconfined or apparmor=unconfined, for example with docker inspect --format '{{.HostConfig.Privileged}} {{.HostConfig.SecurityOpt}}'. Strip those rights or stop the workloads wherever the business allows.
      • Disable unprivileged user namespaces where they are not needed: sysctl -w kernel.unprivileged_userns_clone=0 (Debian/Ubuntu) or user.max_user_namespaces=0. Persist the setting in /etc/sysctl.d/.
      • Compromise sweep: On container hosts, look for populated release_agent files in mounted cgroup v1 hierarchies (find /sys/fs/cgroup -name release_agent -size +0). Also check whether any container has mounted cgroupfs itself.

    2. Runbook step 2

      Mitigation layers

      • Syscall filtering: The default Docker/containerd seccomp profile blocks mount and unshare, which kills the known exploit path. In Kubernetes, enforce seccompProfile: RuntimeDefault cluster-wide via Pod Security Admission (restricted or baseline).
      • Mandatory access control: Keep AppArmor (docker-default) or SELinux (container_t) in enforcing mode, since both prevent cgroupfs mounts from inside a container. Add aa-status and getenforce checks to configuration monitoring.
      • Least privilege for workloads: Run containers as non-root (runAsNonRoot: true), with allowPrivilegeEscalation: false and capabilities.drop: [ALL]. Use admission policies (Kyverno/OPA Gatekeeper) to reject privileged and SYS_ADMIN.
      • Move to cgroup v2: release_agent exists only in cgroup v1. Switching with systemd.unified_cgroup_hierarchy=1 removes the attack surface entirely. Validate container runtime compatibility first.
      • Isolate execution environments: Run CI runners and build systems that execute third-party code on dedicated, ephemeral VMs rather than shared hosts. An escape then only lands on a disposable instance.

    3. Runbook step 3

      Detection rules

      • auditd – release_agent writes: Use -a always,exit -F arch=b64 -S mount -F a2=cgroup -k cgroup_mount plus -w /sys/fs/cgroup/ -p w -k cgroup_write. Alert on writes to release_agent or notify_on_release from processes inside a container namespace.
      • Falco: Enable the stock rule "Detect release_agent File Container Escapes". Add evt.type=mount and container.id!=host and fd.name contains cgroup.
      • Process ancestry (EDR / Sysmon for Linux EID 1): Watch for shell or script interpreters (sh, bash, python) whose parent is a kernel thread (kworker, PPID 2 / kthreadd) and whose image path sits under /var/lib/docker/overlay2/ or /run/containerd/. This is the call_usermodehelper signature of a triggered release_agent.
      • Exploit staging: Watch for unshare -UrmC or unshare --user --map-root-user executed inside containers, followed by mount -t cgroup. Sigma shape: process.name=unshare AND cmdline contains "-U" AND container.id exists.
      • Kubernetes audit log: Pod creation with securityContext.privileged=true or capabilities.add containing SYS_ADMIN by ServiceAccounts that are not on the allow-list.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A vulnerability was found in the Linux kernel’s cgroup_release_agent_write in the kernel/cgroup/cgroup-v1.c function. This flaw, under certain circumstances, allows the use of the cgroups v1 release_agent feature to escalate privileges and bypass the namespace isolation unexpectedly.

    Source: BSI CSAF, BSI WID Portal, OSV (Open Source Vulnerabilities), CSA/SingCERT, Debian Security Advisories, NVD (NIST), cvelistv5, CISA KEV Catalog

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    —kernel
    • kernel 5.17 rc3
    • —
    netappsolidfire\,_enterprise_sds_\&_hci_storage_node
    • —
    • —
    netappsolidfire_\&_hci_management_node
    • —
    • —
    redhatcodeready_linux_builder
    • 8.2
    • 8.0
    • —
    • —
    redhatcodeready_linux_builder_for_power_little_endian
    • 8.0
    • 8.2
    • —
    • —
    redhatvirtualization_host
    • 4.0
    • —
    Hitachi EnergyAPM Edge
    • < v6.3
    • v6.3
    IBMQRadar SIEM
    • 7.5
    • 7.4
    • —
    • —
    android:linux_kernel:
    • :0
    • Kernel
    • :2022-06-05
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux10.0
    Linuxdebiandebian_linux11.0
    Linuxdebiandebian_linux9.0
    Linuxredhatenterprise_linux8.0
    Linuxredhatenterprise_linux_eus8.2
    Linuxredhatenterprise_linux_for_ibm_z_systems8.0
    Linuxredhatenterprise_linux_for_ibm_z_systems_eus8.0
    Linuxredhatenterprise_linux_for_power_little_endian8.0
    Linuxredhatenterprise_linux_for_power_little_endian_eus8.0
    Linuxredhatenterprise_linux_for_real_time_for_nfv_tus8.0
    Linuxredhatenterprise_linux_for_real_time_for_nfv_tus8.2
    Linuxredhatenterprise_linux_for_real_time_tus8.0
    Linuxredhatenterprise_linux_for_real_time_tus8.2
    Linuxredhatenterprise_linux_server_aus8.2
    Linuxredhatenterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions8.1
    Linuxredhatenterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions8.2
    Linuxredhatenterprise_linux_server_tus8.2
    Linuxredhatenterprise_linux_server_update_services_for_sap_solutions8.1
    Linuxredhatenterprise_linux_server_update_services_for_sap_solutions8.2
    Linuxdebianlinuxbullseye
    Linuxdebianlinuxbuster
    Linuxlinuxlinux_kernel5.17
    Linuxlinuxlinux_kernel—
    Linuxcanonicalubuntu_linux14.04

    Weakness classes (CWE)

    • CWE-287Improper Authentication

      Class

      When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

      Entry at MITRE CWE-287

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    CSA/SingCERTHigh-Severity Vulnerability in Linux Kernel (opens in a new tab)CSA/SingCERTactively exploited
    Packet StormKernel Live Patch Security Notice LSN 0085 1 (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormKernel Live Patch Security Notice LSN 0086 1 (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormDocker cgroups Container Escape (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    PoC-in-GitHub (nomi-sec)CVE-stand (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    Linked advisories

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    Badge preview for CVE-2022-0492
    <a href="https://intel.neosec.eu/en/cve/CVE-2022-0492"><img src="https://intel.neosec.eu/badge/cve/CVE-2022-0492.svg?lang=en" alt="CVE-2022-0492 – NEOSEC Intel" height="20"></a>