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CVE-2026-18686

CRITICAL

CVE-2026-18686 is a critical-severity (CVSS 9.8) CWE-74 vulnerability. O3 Security confirms whether CVE-2026-18686 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

A vulnerability was detected in GL.iNet GL-MT3000 up to 4.4.5. The affected element is the function nas-web.add_user of the file /cgi-bin/glc of the component nas-web RPC Wrapper. Performing…

Published
Aug 4, 2026
Updated
Aug 4, 2026
Affected
0 pkgs
Patched
None yet
Exploits
None indexed

Description

A vulnerability was detected in GL.iNet GL-MT3000 up to 4.4.5. The affected element is the function nas-web.add_user of the file /cgi-bin/glc of the component nas-web RPC Wrapper. Performing a manipulation results in command injection. The attack can be initiated remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure and confirmed the existence of the vulnerability.

Detection & mitigation playbook

Vulnerability
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Remediation status

    No patched version of the affected component has shipped for CVE-2026-18686 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-18686 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-18686. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

A vulnerability was detected in GL.iNet GL-MT3000 up to 4.4.5. The affected element is the function nas-web.add_user of the file /cgi-bin/glc of the component nas-web RPC Wrapper. Performing a manipulation results in command injection. The attack can be initiated remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure and confirmed the existence of the vulnerability.
O3 Security · Impact-Aware SCA

Is CVE-2026-18686 in your dependencies?

O3 detects CVE-2026-18686 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.