Cve 2018 14634 Linux Kernel Vulnerability Cisa Kev

CISA KEV Alert: Legacy Linux Kernel Vulnerability Under Active Exploitation

TechOwl TechOwl January 30, 2026
CISA KEV Alert: Legacy Linux Kernel Vulnerability Under Active Exploitation

CVE-2018-14634: CISA Confirms Active Exploitation of Legacy Linux Kernel Vulnerability

Executive Summary

On January 26, 2026, the Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2018-14634 to its Known Exploited Vulnerabilities (KEV) catalog. This Linux kernel privilege escalation vulnerability, originally disclosed in September 2018 and designated "Mutagen Astronomy" by Qualys researchers, has been confirmed as actively exploited in current threat campaigns. The vulnerability affects systems running end-of-life CentOS and Red Hat Enterprise Linux distributions, as well as enterprise appliances from F5 Networks and Palo Alto Networks.

Key Findings

  • Integer overflow vulnerability in Linux kernel's create_elf_tables() function enables local privilege escalation to root
  • CVSS Score: 7.8 (High) with complete confidentiality, integrity, and availability impact
  • Affects kernel versions 2.6.x, 3.10.x, and 4.14.x across multiple Linux distributions
  • 49% of organizations maintain CentOS workloads despite end-of-life status
  • 200,000+ CentOS Web Panel instances and 44,000+ CentOS systems identified via internet scanning
  • Enterprise appliances including F5 Big-IP and Palo Alto PAN-OS confirmed vulnerable
  • CISA remediation deadline: February 16, 2026

Vulnerability Profile

Attribute Value
CVE Identifier CVE-2018-14634
Designation Mutagen Astronomy
CVSS v3.0 Score 7.8 (High)
CVSS Vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE Classification CWE-190: Integer Overflow or Wraparound
Affected Function create_elf_tables() in fs/binfmt_elf.c
Attack Vector Local
Privileges Required Low (local user access)
Exploitation Status Active (CISA Confirmed)

Affected Systems

Linux Kernel Versions

The vulnerability affects Linux kernel versions containing commit b6a2fea39318 (July 19, 2007) but lacking commit da029c11e6b1 (July 7, 2017):

Kernel Branch Affected Versions
Linux 2.6.x 2.6.0 through 2.6.39.4
Linux 3.10.x 3.10.0 through 3.10.102
Linux 4.14.x 4.14.0 through 4.14.54

Linux Distributions

Distribution End-of-Life Date Patch Availability
CentOS 6 November 30, 2020 Discontinued
CentOS 7 June 30, 2024 Discontinued
CentOS 8 December 31, 2021 Discontinued
RHEL 6 November 30, 2020 Extended support only
RHEL 7 June 30, 2024 Extended support only
Ubuntu 12.04 ESM April 2017 Extended support only
Ubuntu 14.04 LTS April 2019 Extended support only
Debian 8 June 2020 Discontinued

Enterprise Appliances

F5 Networks Big-IP:

  • Versions 11.2.1 through 11.6.3
  • Versions 12.1.0 through 12.1.4
  • Versions 13.0.0 through 13.1.1.4
  • Versions 14.0.0 through 14.1.0.5

Palo Alto Networks PAN-OS:

  • Versions 7.1.0 through 7.1.22
  • Versions 8.0.0 through 8.0.15
  • Versions 8.1.0 through 8.1.6

Technical Analysis

Vulnerability Mechanism

The vulnerability exists in the create_elf_tables() function responsible for setting up the initial stack during ELF binary execution. When processing command-line arguments and environment variables, an integer overflow can occur in the size calculation, leading to stack corruption and arbitrary code execution.

Exploitation Requirements

Requirement Description
Architecture 64-bit system required (32-bit systems not exploitable)
System Memory 32GB or greater RAM
Access Level Local user access to target system
SUID Binary Presence of a SUID-root binary
Stack Limit Ability to set RLIMIT_STACK to unlimited

Memory Requirement Analysis

The substantial memory requirement stems from the exploitation methodology:

Argument Count:     2^31 = 2,147,483,648 items
Pointer Size:       8 bytes (64-bit architecture)
argv Array Size:    2^31 × 8 = 16 GB
Environment Padding: ~16 GB additional
────────────────────────────────────
Total Memory:       ~32 GB minimum

Exploitation Flow

Stage Action Technical Detail
1 Preparation Attacker crafts execve() call with ~2^31 command-line arguments
2 Environment Setup Malicious LD_PRELOAD and LD_LIBRARY_PATH environment variables configured
3 Memory Allocation Memory-mapped file created for argv array efficiency (~16GB)
4 Overflow Trigger Integer overflow occurs in create_elf_tables() size calculation
5 Stack Corruption Kernel allocates insufficient buffer; massive data write corrupts stack
6 Privilege Escalation SUID binary executes with corrupted stack; attacker gains root privileges

Exposure Assessment

Internet Exposure Statistics

Metric Value Source
Organizations with CentOS workloads 49% Orca Security
CentOS share of Linux deployments 26.05% Lansweeper
Internet-exposed CentOS systems 44,111+ Shodan
CentOS Web Panel instances 200,000+ Shodan
Vulnerable F5 Big-IP instances 39+ Shodan

Threat Actor Utility

CVE-2018-14634 functions as a post-compromise capability, providing privilege escalation following initial access obtained through alternative vectors. This positions the vulnerability as valuable for:

  • Ransomware Operations: Elevated privileges enable comprehensive file system encryption and security control disablement
  • Advanced Persistent Threat (APT) Campaigns: Root access facilitates persistent implant installation and credential harvesting
  • Container Infrastructure Compromise: Exploitation on container hosts affects all containerized workloads
  • Lateral Movement: Administrative credentials obtained post-exploitation enable network propagation

MITRE ATT&CK Mapping

Tactic Technique ID Technique Name Evidence
Privilege Escalation T1068 Exploitation for Privilege Escalation Integer overflow in kernel function
Privilege Escalation T1548.001 Abuse Elevation Control Mechanism: Setuid and Setgid SUID binary abuse for privilege escalation
Defense Evasion T1574.006 Hijack Execution Flow: Dynamic Linker Hijacking LD_PRELOAD environment manipulation
Execution T1203 Exploitation for Client Execution Memory corruption via crafted arguments

Detection Opportunities

Endpoint Detection

Process Monitoring:

  • Processes spawned with abnormally high argument counts (approaching 2^31)
  • SUID binary execution from non-standard contexts or user accounts
  • Resource limit modifications (specifically RLIMIT_STACK set to unlimited)

Environment Variable Monitoring:

LD_PRELOAD manipulation attempts
LD_LIBRARY_PATH modifications in privilege escalation context

System Audit Commands:

# Identify current kernel version
uname -r

# Enumerate distribution information
cat /etc/os-release

# Inventory SUID binaries
find / -perm -4000 -type f 2>/dev/null

Network Detection

While CVE-2018-14634 is a local privilege escalation vulnerability, network monitoring can detect related attack chain activity:

  • Initial access attempts via SSH brute force or credential stuffing
  • Lateral movement following successful exploitation
  • Data exfiltration from compromised hosts

Remediation Guidance

Immediate Actions

Priority Action Description
Critical Asset Inventory Identify all systems running affected kernel versions (2.6.x, 3.10.x, 4.14.x)
Critical Internet Exposure Assessment Identify vulnerable systems with internet exposure
High Migration Planning Develop migration timelines for EOL distributions
High Appliance Assessment Review F5 Big-IP and Palo Alto PAN-OS firmware versions
Medium SUID Binary Audit Review and minimize SUID binary deployment
Medium Detection Implementation Deploy monitoring for privilege escalation indicators

Migration Options

For organizations operating end-of-life CentOS distributions:

  • AlmaLinux: Binary-compatible CentOS replacement (community-supported)
  • Rocky Linux: Binary-compatible CentOS replacement (community-supported)
  • Red Hat Enterprise Linux: Commercial support available
  • Ubuntu LTS: Long-term support releases available

Extended Support Options

Where immediate migration is not feasible:

  • TuxCare Extended Lifecycle Support: Continued security patches for EOL distributions
  • Red Hat Extended Life Cycle Support: Extended support for RHEL customers

Timeline

Date Event
July 19, 2007 Vulnerable code introduced (commit b6a2fea39318)
July 7, 2017 Remediation committed to mainline kernel (commit da029c11e6b1)
September 25, 2018 Public disclosure by Qualys ("Mutagen Astronomy")
September 26, 2018 Proof-of-concept published (Exploit-DB 45516)
November 30, 2020 CentOS 6 end-of-life
December 31, 2021 CentOS 8 end-of-life
June 30, 2024 CentOS 7 end-of-life
January 26, 2026 CISA adds CVE-2018-14634 to KEV catalog
February 16, 2026 CISA remediation deadline

References

Conclusion

The addition of CVE-2018-14634 to CISA's Known Exploited Vulnerabilities catalog underscores the persistent risk posed by end-of-life software in enterprise environments. Despite the availability of patches since 2017, substantial deployment of unpatched systems continues to provide viable attack surface for threat actors.

The vulnerability's continued exploitation eight years after disclosure demonstrates that technical debt in operating system lifecycle management represents measurable organizational risk. Organizations maintaining CentOS or RHEL deployments should treat this KEV addition as an indicator of active threat actor interest and prioritize identification and remediation of affected systems.

With 49% of organizations still maintaining CentOS workloads and all CentOS versions now past end-of-life, the attack surface for this vulnerability remains substantial. Organizations must accelerate migration initiatives and implement enhanced monitoring to detect exploitation attempts targeting legacy Linux infrastructure.

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