CVERadar
HIGH · CVSS 3.1 8.8CISA KEV · added 2025-06-02EPSS 39.51% (p99)Threat level 71

CVE-2023-39780: ASUS RT-AX55 Routers OS Command Injection Vulnerability

ASUS · RT-AX55 Routers · NVD published 2023-09-12 · posted 2025-06-02 · last modified 2026-06-17

What it is

On ASUS RT-AX55 3.0.0.4.386.51598 devices, authenticated attackers can perform OS command injection via the /start_apply.htm qos_bw_rulelist parameter. NOTE: for the similar "token-generated module" issue, see CVE-2023-41345; for the similar "token-refresh module" issue, see CVE-2023-41346; for the similar "check token module" issue, see CVE-2023-41347; and for the similar "code-authentication module" issue, see CVE-2023-41348.

WeaknessCWE-78
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (source: [email protected])
CISA due date2025-06-23 (for US federal agencies under BOD; a good deadline for everyone)
ATT&CK tacticsResource Development → Initial Access → Persistence → Privilege Escalation → Stealth → Execution → Lateral Movement

Exploitation evidence

First exploit evidence seen: 2025-06-02 (earliest date across the sources below).

Exploited in the wild

  • CISA KEV: listed since 2025-06-02. Source

Sources: CISA KEV.

Defend the Chain

The attack chain for CVE-2023-39780 laid across the MITRE ATT&CK Enterprise tactics. Solid cards come from the MITRE CTID KEV mappings; dashed cards are inferred by CVERadar from the CWE or description. Correct defences are real ATT&CK mitigations for that technique.

Threat level 71/100
Defender level 1 · 0 XP
Chain links broken: 0/5

Reconnaissance

Resource Development

Initial Access

Execution

Persistence

Privilege Escalation

Stealth

Defense Impairment

Credential Access

Discovery

Lateral Movement

Collection

Command and Control

Exfiltration

Impact

Pick a red technique card on the board, then choose the defence that stops it.

Defend against T1588 Obtain Capabilities CTID: exploitation technique

Attackers have gained access to affected ASUS routers by using brute-force login attempts and authentication bypasses, allowing them to inject and execute commands to enable SSH. Additionally, they can place a backdoor in the NVRAM.

How to fix it

CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. (source: CISA KEV)

Fixed versions

NVD does not list a fixed version for this CVE. Use the vendor advisory below.

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

MITRE ATT&CK mitigations for this chain

  • M1056 Pre-compromise (for T1588) : This technique cannot be easily mitigated with preventive controls since it is based on behaviors performed outside of the scope of enterprise defenses and controls.
  • M1021 Restrict Web-Based Content (for T1133) : Restrict all traffic to and from public Tor nodes.
  • M1030 Network Segmentation (for T1133) : Deny direct remote access to internal systems through the use of network proxies, gateways, and firewalls.
  • M1042 Disable or Remove Feature or Program (for T1133, T1021.004) : Disable or block remotely available services that may be unnecessary.
  • M1035 Limit Access to Resource Over Network (for T1133) : Limit access to remote services through centrally managed concentrators such as VPNs and other managed remote access systems.
  • M1032 Multi-factor Authentication (for T1133, T1078, T1021.004) : Use strong two-factor or multi-factor authentication for remote service accounts to mitigate an adversary's ability to leverage stolen credentials, but be aware of [Multi-Factor Authentication Interception](https://attack.mitre.org/techniques/T1111) techniques for some two-factor authentication implementations.
  • M1027 Password Policies (for T1078) : Applications and appliances that utilize default username and password should be changed immediately after the installation, and before deployment to a production environment. When possible, applications that use SSH keys should be updated periodically and properly secured. Policies should minimize (if not eliminate)
  • M1018 User Account Management (for T1078, T1021.004) : Regularly audit user accounts for activity and deactivate or remove any that are no longer needed.
  • M1026 Privileged Account Management (for T1078) : Audit domain and local accounts as well as their permission levels routinely to look for situations that could allow an adversary to gain wide access by obtaining credentials of a privileged account. These audits should also include if default accounts have been enabled, or if new local accounts are created that have
  • M1013 Application Developer Guidance (for T1078) : Ensure that applications do not store sensitive data or credentials insecurely. (e.g. plaintext credentials in code, published credentials in repositories, or credentials in public cloud storage).

Detection Generic guidance

  • Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
  • Persistence: Look for new files in web roots, new scheduled tasks/services, and new accounts created after the exposure window.
  • Privilege Escalation: Alert on processes gaining SYSTEM/root unexpectedly, and on exploitation crashes of privileged services.
  • Execution: Watch for the service process spawning shells or script interpreters (cmd.exe, powershell, sh, bash, python) via EDR process-tree rules.
  • Lateral Movement: Watch for the compromised host authenticating to other internal systems it does not normally talk to.

Response checklist Generic guidance

  1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
  2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
  3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
  4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.

Sources