CriticalCVE-2024-1086

    Linux Kernel Use-After-Free Vulnerability (CVE-2024-1086)

    Published Last modified In CISA KEV since Sources: pwn.watch, CVE.org

    What is affected, what to do

    A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The nft_verdict_init() function allows positive values as drop error within the hook verdict, and hence the nf_hook_slow() function can cause a double free vulnerability when NF_DROP is issued with a drop error which resembles NF_ACCEPT.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update Linux Kernel to version 6.8. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Linux Kernel lt 3.15..6.8
    Fixed in
    • Linux Kernel 6.8

    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: pwn.watch, CVE.org

    28.1 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.1

    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
    245.37 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 exploited
    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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    28.1 %
    Elevated — model estimates 10-50% 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
    98.1
    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 13 June 2024
    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-416

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This is a reliable local root escalation spanning roughly a decade of kernel releases, with a public exploit that works across major distributions; CISA flags known ransomware use, where it turns an initial low-privilege foothold on a Linux server into full host control ahead of data theft and encryption. Although it needs local low-privilege access, exploitation likelihood is very high and it fully defeats container and tenant isolation. Treat container hosts, CI/CD runners, multi-user and internet-facing servers as top priority; isolated single-purpose appliances without shell access can follow in the regular patch cycle provided unprivileged user namespaces are disabled.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory kernels now: Collect uname -r from every Linux host (Ansible/Salt/EDR inventory) and compare against fixed upstream releases: 5.15.149, 6.1.76, 6.6.15, 6.7.3 or 6.8 and later (commit f342de4e2f33e0e39165d8639387aa6c19dff660). For distribution kernels (Debian 10, Fedora 39, RHEL, Ubuntu, SUSE) the distro backport is what counts — patch available from the vendor, look up the exact package version in the distribution advisory.
      • Patch and reboot in priority order: Container hosts (Kubernetes nodes, Docker hosts), CI/CD runners, jump hosts, shared-hosting and multi-user servers first. The fix is not active until reboot; check whether a livepatch (Ubuntu Livepatch, kpatch, SUSE Live Patching) covers your kernel build.
      • Disable unprivileged user namespaces where a reboot must wait: sysctl -w user.max_user_namespaces=0, or on Debian/Ubuntu sysctl -w kernel.unprivileged_userns_clone=0, persisted under /etc/sysctl.d/. The public exploit relies on obtaining CAP_NET_ADMIN inside a user namespace.
      • Block nf_tables where unused: On hosts not running nftables/firewalld, add install nf_tables /bin/false to /etc/modprobe.d/disable-nftables.conf and verify with lsmod | grep nf_tables. Caution: firewalld and iptables-nft backends depend on it.
      • Assume escalation on already-compromised hosts: Where initial access is known or suspected (webshell, abused service account), treat root as lost — rotate root credentials, SSH host keys and any secrets stored on the box (kubeconfigs, cloud tokens).

    2. Runbook step 2

      Mitigation layers

      • Kernel configuration: Set user.max_user_namespaces=0 on servers that don't need rootless containers, browser sandboxes or Flatpak. On Ubuntu 23.10+ keep kernel.apparmor_restrict_unprivileged_userns=1 enabled.
      • Container isolation: Run pods with seccompProfile: RuntimeDefault (blocks unprivileged unshare/clone(CLONE_NEWUSER)), allowPrivilegeEscalation: false, and never grant CAP_NET_ADMIN or CAP_SYS_ADMIN. Enforce via Pod Security Admission (restricted) or Kyverno/OPA Gatekeeper.
      • IAM / least privilege: Strip interactive shells from service accounts (/usr/sbin/nologin) and minimise who can log in to servers. Because exploitation requires a local foothold, every removed shell directly shrinks exposure.
      • Network segmentation: This bug is the second stage of a chain (web RCE, stolen SSH credentials). Isolate internet-facing Linux services in dedicated zones and restrict server egress to allowlists to hinder exploit download and C2.
      • Execution control: Mount /tmp, /dev/shm and /var/tmp with noexec; where EDR allows, block execution of unsigned ELF binaries from these paths by web or service accounts.

    3. Runbook step 3

      Detection rules

      • auditd — namespace creation by unprivileged users: -a always,exit -F arch=b64 -S unshare -F auid>=1000 -F auid!=4294967295 -k userns_create, plus -S clone filtered for CLONE_NEWUSER. Hits from www-data, nginx or service accounts warrant immediate triage.
      • auditd — module loads: -a always,exit -F arch=b64 -S init_module,finit_module -k modload; an unexpected nf_tables load without a corresponding firewall change is suspicious.
      • EDR / Sysmon for Linux — privilege jump in process ancestry: A process with euid=0 whose parent ran as UID ≥ 1000 without sudo, su, pkexec or another setuid helper in the chain. KQL (MDE): DeviceProcessEvents | where AccountName == "root" and InitiatingProcessAccountName != "root" and InitiatingProcessFileName !in~ ("sudo","su","pkexec","sshd","cron").
      • Execution from temp paths: Sigma shape logsource: product=linux, category=process_creation with Image|startswith: ['/tmp/','/dev/shm/','/var/tmp/'] followed by a root-owned /bin/sh or /bin/bash child.
      • Kernel log anomalies: Alert on general protection fault, KASAN: use-after-free, BUG: unable to handle or oops traces referencing nf_tables/nf_hook_slow in dmesg/journald — failed exploit attempts frequently crash or taint the kernel.

    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 use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The nft_verdict_init() function allows positive values as drop error within the hook verdict, and hence the nf_hook_slow() function can cause a double free vulnerability when NF_DROP is issued with a drop error which resembles NF_ACCEPT. We recommend upgrading past commit f342de4e2f33e0e39165d8639387aa6c19dff660.

    Source: pwn.watch, CISA KEV Catalog, cvelistv5, NVD (NIST), CVE.org (MITRE)

    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
    LinuxKernel
    • 3.15 – < 6.8
    • 6.8

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux10.0
    Linuxredhatenterprise_linux_desktop7.0
    Linuxredhatenterprise_linux_for_ibm_z_systems7.0_s390x
    Linuxredhatenterprise_linux_for_power_big_endian7.0_ppc64
    Linuxredhatenterprise_linux_for_power_little_endian7.0_ppc64le
    Linuxredhatenterprise_linux_server7.0
    Linuxredhatenterprise_linux_workstation7.0
    Linuxlinuxlinux_kernel6.8
    Linuxlinuxlinux_kernel—
    Othernetapp500f_firmware—
    Othernetappa250_firmware—
    Othernetappbootstrap_os—
    Othernetappc250_firmware—
    Otherfedoraprojectfedora39
    Othernetapph300s_firmware—
    Othernetapph410c_firmware—
    Othernetapph410s_firmware—
    Othernetapph500s_firmware—
    Othernetapph700s_firmware—

    Weakness classes (CWE)

    • CWE-416Use After Free

      Variant

      The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

      Entry at MITRE CWE-416

    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
    GitHubNotselwyn/CVE-2024-1086 (opens in a new tab)github.comPoC (publicly reported)reported, not verified—
    PoC-in-GitHub (nomi-sec)KOOBE-Guard (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)onetwoseven-writeup (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE_2024_1086_vulnerability_check (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. NVD analysis modifiedNVD

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:*
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:*
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:*
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:h410c:-:*:*:*:*:*:*:*
      Product configurationadded
      —
      AND OR *cpe:2.3:o:netapp:bootstrap_os:-:*:*:*:*:*:*:* OR cpe:2.3:h:netapp:hci_compute_node:-:*:*:*:*:*:*:*

      Source identifier: nvd@nist.gov

    2. Record modifiedgoogle.com

      Description added or changed

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The nft_verdict_init() function allows positive values as drop error within the hook verdict, and hence the nf_hook_slow() function can cause a double free vulnerability when NF_DROP is issued with a drop error which resembles NF_ACCEPT. We recommend upgrading past commit f342de4e2f33e0e39165d8639387aa6c19dff660.
      A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The nft_verdict_init() function allows positive values as drop error within the hook verdict, and hence the nf_hook_slow() function can cause a double free vulnerability when NF_DROP is issued with a drop error which resembles NF_ACCEPT. We recommend upgrading past commit f342de4e2f33e0e39165d8639387aa6c19dff660.

      Source identifier: cve-coordination@google.com

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