Which versions of Totolink A8000RU are affected by EUVD-2026-31670?

The Totolik A8000RU router (firmware 7.1cu.643_b20200521) contains a critical remote code execution vulnerability allowing unauthenticated attackers to execute arbitrary commands through the OpenVPN…

Is there a public PoC exploit available for EUVD-2026-31670?

Yes, a public proof-of-concept exploit is available for EUVD-2026-31670. Prioritise patching immediately. EPSS: 0.9%.

How to fix or mitigate EUVD-2026-31670?

Within 24 hours: Identify all Totolik A8000RU routers in production (particularly firmware 7.1cu.643_b20200521) and immediately restrict network access to their administration interfaces using firewall rules-permit management access only from specific trusted internal IP ranges. Within 7 days: Contact Totolik for patch timeline; implement IDS/IPS detection signatures to monitor requests to /cgi-bin/cstecgi.cgi for command injection patterns; deploy network segmentation to isolate affected devices from high-value systems. Within 30 days: Evaluate replacement options with vendor-supported alternatives; if retention is necessary, implement additional controls such as reverse-proxy authentication or air-gapping from untrusted network segments; mandate firmware updates immediately upon vendor release.

Totolink A8000RU EUVD-2026-31670

Q: What is the CVSS score of EUVD-2026-31670?

EUVD-2026-31670 has a CVSS 4.0 base score of 8.9 (High). CVSS vector: CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.9%.

| CVE-2026-9454 HIGH

OS Command Injection (CWE-78)

2026-05-25 VulDB

GHSA-3h6x-px3r-wh95

Command Injection A8000Ru

8.9

CVSS 4.0 · Vendor: VulDB

Severity by source

Vendor (VulDB) PRIMARY

8.9 HIGH

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from Vendor (VulDB) · only source for this CVE.

CVSS VectorVendor: VulDB

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Jun 08, 2026 - 09:41 vuln.today

Severity Changed

May 26, 2026 - 19:07 NVD

CRITICAL HIGH

CVSS changed

May 26, 2026 - 19:07 NVD

9.8 (CRITICAL) 8.9 (HIGH)

CVE Published

May 25, 2026 - 11:30 nvd

HIGH 8.9

DescriptionCVE.org

A flaw has been found in Totolink A8000RU 7.1cu.643_b20200521. This vulnerability affects the function setOpenVpnCertGenerationCfg of the file /cgi-bin/cstecgi.cgi of the component Web Management Interface. Executing a manipulation of the argument servername can lead to os command injection. The attack may be launched remotely. The exploit has been published and may be used.

AnalysisAI

OS command injection in the Totolink A8000RU router (firmware 7.1cu.643_b20200521) allows remote unauthenticated attackers to execute arbitrary commands via the servername parameter of the setOpenVpnCertGenerationCfg function in /cgi-bin/cstecgi.cgi. Publicly available exploit code exists (GitHub PoC), and although the EPSS score is modest (0.89%, 76th percentile), the CVSS 4.0 score of 8.9 reflects network-reachable, no-privilege, no-interaction exploitation with high confidentiality, integrity, and availability impact. No CISA KEV listing has been recorded at the time of analysis.

Technical ContextAI

The vulnerability resides in cstecgi.cgi, the central CGI handler exposed by the Totolink A8000RU Web Management Interface, which dispatches requests to internal handlers including setOpenVpnCertGenerationCfg used during OpenVPN certificate generation. The servername argument is passed without proper sanitization to an underlying shell invocation, matching CWE-78 (Improper Neutralization of Special Elements used in an OS Command). The affected CPE cpe:2.3:a:totolink:a8000ru:*:*:*:*:*:*:*:* identifies the A8000RU SOHO/SMB router running the vulnerable 7.1cu.643_b20200521 firmware build, a Linux/BusyBox-based platform where shell metacharacter injection typically yields code execution as root.

RemediationAI

No vendor-released patch identified at time of analysis - Totolink has not published a fixed firmware build for the A8000RU in the available references (https://www.totolink.net/, https://nvd.nist.gov/vuln/detail/CVE-2026-9454, https://vuldb.com/vuln/365435). As compensating controls, restrict access to the Web Management Interface to trusted management VLANs only and explicitly disable WAN-side administration in the router configuration (trade-off: remote admin convenience is lost); block inbound TCP to the HTTP/HTTPS admin ports at any upstream firewall; and where feasible, deny requests to /cgi-bin/cstecgi.cgi from non-management subnets via an upstream reverse proxy or ACL (trade-off: may break legitimate management workflows that traverse those networks). Where the device is end-of-life or vendor-unresponsive, plan migration to a supported router model, since command-injection bugs in cstecgi.cgi have been a recurring Totolink issue and unpatched devices are common botnet targets.