Security Resilience

CVE-2023-20025

Auth Bypass in Cisco Rv016 Firmware

Published
20 January 2023
Modified
07 April 2025
Patch / advisory
CVSS Score v3.1 9.0
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.016 76th percentile
Risk Priority 67 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-20025 is a critical-severity Using Referer Field for Authentication (CWE-293) vulnerability in Cisco Rv016 Firmware. Its CVSS base score is 9.0 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked in the top 24% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

A vulnerability in the web-based management interface of Cisco Small Business RV016, RV042, RV042G, and RV082 Routers could allow an unauthenticated, remote attacker to bypass authentication on an affected device. This vulnerability is due to improper validation of user input…

more

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 bypass authentication and gain root access on the underlying operating system.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-20026Same product: Cisco Rv016
CVE-2023-20149Same product: Cisco Rv016
CVE-2023-20141Same product: Cisco Rv016
CVE-2023-20145Same product: Cisco Rv016
CVE-2023-20146Same product: Cisco Rv016
CVE-2023-20137Same product: Cisco Rv016
CVE-2023-20147Same product: Cisco Rv016
CVE-2023-20148Same product: Cisco Rv016
CVE-2023-20139Same product: Cisco Rv016
CVE-2023-20143Same product: Cisco Rv016

Affected Assets

cisco
rv016 firmware
all versions
cisco
rv042 firmware
all versions
cisco
rv042g firmware
all versions
cisco
rv082 firmware
all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V6.4.3
  • V10.4.16
  • V11.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-290

Reveals spoofed logon attempts through unexpected previous logon timestamps upon legitimate login.

addresses: CWE-290

Training specifically addresses recognizing spoofed communications and phishing that enable authentication bypass.

addresses: CWE-290

Requiring verifiable identity evidence at appropriate assurance levels makes it substantially harder for attackers to successfully spoof or impersonate users to obtain accounts.

addresses: CWE-290

Unique device authentication makes successful spoofing of device identity substantially more difficult to achieve.

addresses: CWE-290

Unique identification of non-organizational users reduces the feasibility of authentication bypass by spoofing.

addresses: CWE-290

Unique identification and authentication of services before communications makes spoofing of service identities substantially harder.

addresses: CWE-290

Isolated trusted path ensures the user interacts only with genuine system components, preventing spoofing of authentication interfaces or prompts.

addresses: CWE-290

Directly counters DNS response spoofing by requiring cryptographic origin authentication artifacts from the authoritative source.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-02 partial match
blocks

Proofing and binding identities reduces spoofing opportunities during enrollment but does not address runtime authentication implementation flaws.

PR.AA-03 partial match
blocks

Proper authentication mechanisms directly replace reliance on the spoofable Referer header.

PR.AA-04 partial match
blocks

Ensuring identity assertions are protected and verified eliminates use of an untrusted Referer field.

PR.AA-05 partial match
blocks

Authorization policy enforcement reduces the chance that a weak Referer check is accepted as sufficient.

PR.PS-06 partial match
blocks

Secure-development practices discourage or prohibit using the Referer header for authentication decisions.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

removes
blocks

A.5.15 only requires that an access control policy and requirements be defined and communicated; it does not itself implement, enforce or configure any authentication scheme that would stop spoofing attacks from bypassing authentication, so the weakness remains fully exploitable.

blocks

A.5.16 manages the lifecycle, uniqueness, and accountability of identities; it does not implement or strengthen authentication schemes against spoofing, so the CWE-290 exploit remains possible even when identities are correctly provisioned and tracked.

blocks

Authentication information management directly addresses credential handling that prevents spoofing.

blocks

A.5.18 governs the provisioning, review, and revocation of already-granted access rights to authenticated identities; it has no bearing on whether an authentication scheme can be spoofed or bypassed before any rights are assigned.

removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248827 OL 8 must not have the rsh-server package installed. blocks CWE-290
RHEL 7 (1 rule)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. blocks CWE-290
RHEL 8 (1 rule)
  • V-230492 RHEL 8 must not have the rsh-server package installed. blocks CWE-290

References