CISA Warns of Actively Exploited Linux Kernel Vulnerability (CVE-2024-1086)

The Cybersecurity and Infrastructure Security Agency (CISA) has issued a warning about attackers exploiting a high-severity vulnerability (CVE-2024-1086) in the Linux kernel’s netfilter: nf_tables subsystem. This flaw allows local privilege escalation to root, posing significant risks to federal systems and enterprise environments. A proof-of-concept (PoC) exploit is publicly available, and CISA has mandated patching for federal agencies by June 20, 2024¹.

Summary for CISOs

The vulnerability (CVSSv3 7.8) affects Linux kernels 5.14–6.6, including distributions like Debian, Ubuntu, and RHEL. Exploitation involves memory corruption via malformed nf_tables rulesets, enabling root access. CISA added this flaw to its Known Exploited Vulnerabilities (KEV) catalog on May 30, 2024, indicating active in-the-wild attacks².

Affected Systems: Linux kernels 5.14–6.6 (unpatched versions)
Impact: Local privilege escalation to root via kernel memory corruption
Mitigation: Patch to kernel ≥5.4.269, ≥5.10.210, or ≥6.6.15
Deadline: Federal agencies must remediate by June 20, 2024 (BOD 22-01)

Technical Analysis

CVE-2024-1086 is a use-after-free flaw in the netfilter: nf_tables subsystem. Attackers craft malicious rulesets via unprivileged user namespaces, triggering a double-free condition that corrupts kernel memory. This allows arbitrary code execution with root privileges³. The vulnerability is particularly dangerous because it can be chained with CVE-2023-3390 (an integer overflow in Netfilter) to increase exploit reliability.

Diagnostic steps to check vulnerability status:

uname -r  # Verify kernel version (vulnerable if <6.6.15)

Mitigation and Remediation

Immediate patching is the primary mitigation. For systems where patching isn’t immediately feasible, the following workarounds can reduce risk:

Disable unprivileged user namespaces (if unused):
echo 1 > /proc/sys/kernel/unprivileged_userns_clone
Blocklist the nf_tables module:
echo "blacklist nf_tables" >> /etc/modprobe.d/blacklist.conf

Historical context shows similarities to the “GameOver(lay)” flaws (CVE-2023-0386), which impacted 40% of Ubuntu cloud workloads in 2023⁴.

Additional Exploited Vulnerabilities

CISA’s KEV catalog also highlights other critical flaws requiring attention:

CVE	Impact	Affected Products
CVE-2023-33538	Command injection in TP-Link routers	TL-WR940N V2/V4, TL-WR841N V8/V10
CVE-2025-24016	RCE in Wazuh servers	Wazuh <4.7.5

Strategic Recommendations

Organizations should prioritize patching KEV-listed vulnerabilities and monitor end-of-life products. Defense-in-depth measures like Linux Kernel Runtime Guard (LKRG) can help detect exploitation attempts. Network segmentation is advised for critical systems to limit lateral movement.

CISA provides free resources, including the KEV catalog and Secure by Design guidelines, to assist with vulnerability management⁵.

Conclusion

The exploitation of CVE-2024-1086 underscores the importance of timely patching for Linux systems. With public PoCs and active attacks, organizations must act swiftly to mitigate risks. Federal agencies face a June 20 deadline, but all enterprises running affected kernel versions should prioritize this update.