CVE-2026-18685Public exploitNetwork attack vectorHinoki check available

Unauthenticated root command execution via unquoted firmware_upload

Published Aug 3, 2026 · Updated Aug 3, 2026

Command injection in modem.so on GL.iNet Beryl AX firmware 4.4.0 through 4.4.5 allows remote attackers to execute commands as root. The set_upgrade handler inserts the firmware_upload JSON value into the first unquoted %s of a shell command, then passes the resulting string to /bin/sh -c. The endpoint requires no authentication, but exploitation requires a connected modem to satisfy a separate check on modem_url; successful injection grants root command execution.

CVSS severity9.8
Critical
EPSS probability1.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Command injection in modem.so on GL.iNet Beryl AX firmware 4.4.0 through 4.4.5 allows remote attackers to execute commands as root. The set_upgrade handler inserts the firmware_upload JSON value into the first unquoted %s of a shell command, then passes the resulting string to /bin/sh -c. The endpoint requires no authentication, but exploitation requires a connected modem to satisfy a separate check on modem_url; successful injection grants root command execution.

The record

CVE
CVE-2026-18685
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
GL.iNet
Product
GL-MT3000
Classifications
CWE-74, CWE-77, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.0
  2. Affected versionversion=4.4.1
  3. Affected versionversion=4.4.2
  4. Affected versionversion=4.4.3
  5. Affected versionversion=4.4.4
  6. Affected versionversion=4.4.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GL.iNet · GL-MT3000version=4.4.0; version=4.4.1; version=4.4.2; version=4.4.3; version=4.4.4; version=4.4.5

Published CVSS scores

9.8VulDB CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.9VulDB CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
10.0VulDB CNAAV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-77Command Injection
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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