CVE-2023-20118: Cisco Small Business RV Series Routers Command Injection Vulnerability
Cisco · Small Business RV Series Routers · NVD published 2023-04-13 · posted 2025-03-03 · last modified 2026-06-17
What it is
A vulnerability in the web-based management interface of Cisco Small Business Routers RV016, RV042, RV042G, RV082, RV320, and RV325 Routers could allow an authenticated, remote attacker to execute arbitrary commands on an affected device. This vulnerability is due to improper validation of user input within incoming HTTP packets. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web-based management interface. A successful exploit could allow the attacker to gain root-level privileges and access unauthorized data. To exploit this vulnerability, an attacker would need to have valid administrative credentials on the affected device. Cisco has not and will not release software updates that address this vulnerability. However, administrators may disable the affected feature as described in the Workarounds ["#workarounds"] section. {{value}} ["%7b%7bvalue%7d%7d"])}]]
| Weakness | CWE-77 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H (source: [email protected]) |
| CISA due date | 2025-03-24 (for US federal agencies under BOD; a good deadline for everyone) |
| ATT&CK tactics | Initial Access → Persistence → Privilege Escalation → Stealth → Execution |
Exploitation evidence
First exploit evidence seen: 2025-03-03 (earliest date across the sources below).
Exploited in the wild
- CISA KEV: listed since 2025-03-03. Source
Sources: CISA KEV.
Defend the Chain
The attack chain for CVE-2023-20118 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.
Pick a red technique card on the board, then choose the defence that stops it.
Defend against T1078 Valid Accounts CTID: exploitation technique
Cisco Small Business Router models RV016, RV042, RV042G, RV082, RV320, and RV325 perform improper validation of HTTP packet user input. An authenticated attacker can craft these requests and send them, leading to arbitrary command execution.
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
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sbr042-multi-vuln-ej76Pke5 (CISA KEV notes)
MITRE ATT&CK mitigations for this chain
- 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, T1505.003) : Regularly audit user accounts for activity and deactivate or remove any that are no longer needed.
- M1026 Privileged Account Management (for T1078, T1059) : 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
- M1032 Multi-factor Authentication (for T1078) : Implement multi-factor authentication (MFA) across all account types, including default, local, domain, and cloud accounts, to prevent unauthorized access, even if credentials are compromised. MFA provides a critical layer of security by requiring multiple forms of verification beyond just a password. This measure sign
- 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).
- M1017 User Training (for T1078) : Applications may send push notifications to verify a login as a form of multi-factor authentication (MFA). Train users to only accept valid push notifications and to report suspicious push notifications.
- M1015 Active Directory Configuration (for T1078) : Disable legacy authentication, which does not support MFA, and require the use of modern authentication protocols instead.
- M1036 Account Use Policies (for T1078) : Use conditional access policies to block logins from non-compliant devices or from outside defined organization IP ranges.
- M1033 Limit Software Installation (for T1059) : Prevent user installation of unrequired command and scripting interpreters.
- M1045 Code Signing (for T1059) : Where possible, only permit execution of signed scripts.
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.
Response checklist Generic guidance
- Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
- Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
- Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
- Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.