CVE-2024-1086: Linux Kernel Vulnerability Exploited by Ransomware Gangs

Published by Eclipse Threat Research Team (ETRT)
Date: November 2025
Category: Vulnerability Intelligence | Privilege Escalation | Linux Security

Overview

CVE-2024-1086 is a critical use-after-free vulnerability in the Linux kernel’s netfilter subsystem (nf_tables). The flaw originates from improper memory handling in the nft_verdict_init() and nf_hook_slow() functions. Successful exploitation allows local attackers to escalate privileges to root, bypassing Linux protection mechanisms and enabling ransomware deployment, data exfiltration, and persistent unauthorized access.

Technical Breakdown

The vulnerability stems from logic flaws during verdict handling within nft_verdict_init(), particularly when nf_hook_slow() processes conflicting actions like NF_DROP combined with error discards akin to NF_ACCEPT. This sequence leads to double-free memory operations, letting attackers control freed kernel blocks.

By leveraging unprivileged user namespaces, attackers can reach nf_tables even under default configurations across popular distributions (Debian, Ubuntu, Fedora, Red Hat, and derivatives).
Once exploited, adversaries often modify the modprobe_path variable, spawning a root shell or triggering kernel panic, jeopardizing system stability.

Testing confirms exploitation reliability between 93%–99% under lab conditions, though real-world outcomes vary. Advanced actors have already refined methods for stealthier persistence.

Exploitation in the Wild

• CISA KEV Inclusion: Added May 30 2024, citing ransomware operators abusing this flaw in federal and commercial systems.
• Dark-Web Activity: ETRT observed active chatter and PoC exchanges across Russian-language cybercrime forums (notably XSS) and Telegram channels.
  • Actor “doesenemo” on XSS requested assistance exploiting the kernel crash condition.
  • Public PoC repositories, including github[.]com/Notselwyn/CVE-2024-1086, are circulating widely.
• Attack Chain: Exploitation generally occurs post-initial compromise, following credential theft or phishing footholds. Attackers then elevate privileges, deploy payloads, and tamper with kernel modules to hinder detection.

Threat Landscape Insights

Eclipse Intel’s telemetry indicates that CVE-2024-1086 has become a preferred privilege-escalation vector in Linux-based ransomware playbooks throughout 2024–2025.
Threat actors increasingly bundle kernel exploits within automated scripts to propagate across cloud and containerized workloads, mirroring earlier escalation trends observed in CVE-2022-0847 (“Dirty Pipe”).

Mitigation & Defensive Actions

1. Patch Immediately:
   Upgrade to the latest vendor-patched kernel releases.
   • Debian / Ubuntu → 5.15+ LTS
   • Fedora / RHEL → 6.6+ series
   • Verify with uname -r and vendor advisories.
2. If Patching Is Delayed:
   • Disable unprivileged user namespaces: sysctl -w kernel.unprivileged_userns_clone=0
   • Restrict nf_tables access or unload modules not required in production.
   • Harden monitoring: Detect rapid privilege escalation or kernel module manipulation events.
3. Operational Hardening:
   • Enforce least-privilege principles and audit kernel-level permissions.
   • Document configuration changes for compliance.
   • Segment critical infrastructure and maintain kernel-level telemetry for anomaly detection.

Strategic Outlook

Given its inclusion in CISA’s KEV and continued dark-web interest, CVE-2024-1086 will likely remain a go-to escalation technique for ransomware and APT groups throughout 2025.
Organizations should treat this as a tier-one vulnerability in patch management cycles and monitor Linux endpoints for post-exploitation artifacts even after updates are applied.

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