Which versions of Totolink A8000RU are affected by CVE-2026-7538?

CVE-2026-7538 is a critical remote code execution vulnerability affecting Totolik A8000RU routers running firmware 7.1cu.643_b20200521, allowing unauthenticated attackers to execute arbitrary…

Is there a public PoC exploit available for CVE-2026-7538?

Yes, a public proof-of-concept exploit is available for CVE-2026-7538. Prioritise patching immediately. EPSS: 0.9%.

How to fix or mitigate CVE-2026-7538?

Within 24 hours: Identify and inventory all Totolik A8000RU devices running firmware version 7.1cu.643_b20200521 using network scanning tools; immediately isolate affected devices from internet-facing networks or disable remote management. Within 7 days: Contact Totolik support to confirm available firmware versions beyond 7.1cu.643_b20200521; test firmware upgrade procedures in isolated lab environment. Within 30 days: Deploy verified patched firmware to all affected A8000RU devices; document and verify successful upgrades across inventory.

Totolink A8000RU CVE-2026-7538

Q: What is the CVSS score of CVE-2026-7538?

CVE-2026-7538 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%.

EUVD-2026-26470 HIGH

OS Command Injection (CWE-78)

2026-05-01 VulDB

Command Injection A8000Ru

8.9

CVSS 4.0 · NVD

Severity by source

NVD 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 NVD · only source for this CVE.

CVSS VectorNVD

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

PoC Detected

May 01, 2026 - 15:26 vuln.today

Public exploit code

Analysis Generated

May 01, 2026 - 02:30 vuln.today

Severity Changed

May 01, 2026 - 02:22 NVD

CRITICAL HIGH

CVSS changed

May 01, 2026 - 02:22 NVD

9.8 (CRITICAL) 8.9 (HIGH)

EUVD ID Assigned

May 01, 2026 - 02:15 euvd

EUVD-2026-26470

Analysis Generated

May 01, 2026 - 02:15 vuln.today

CVE Published

May 01, 2026 - 01:30 nvd

HIGH 8.9

DescriptionCVE.org

A vulnerability was identified in Totolink A8000RU 7.1cu.643_b20200521. This issue affects the function Vulnerability of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. The manipulation of the argument proto leads to os command injection. The attack may be initiated remotely. The exploit is publicly available and might be used.

AnalysisAI

OS command injection in Totolink A8000RU firmware 7.1cu.643_b20200521 allows remote unauthenticated attackers to execute arbitrary system commands via the 'proto' parameter in /cgi-bin/cstecgi.cgi CGI handler. A public proof-of-concept exploit exists on GitHub, significantly lowering the barrier for exploitation. CVSS 8.9 with network vector, low complexity, and no authentication requirements makes this immediately exploitable against internet-facing devices running the vulnerable firmware version.

Technical ContextAI

This vulnerability (CWE-78: OS Command Injection) occurs in the CGI handler component of Totolink A8000RU wireless router firmware. The /cgi-bin/cstecgi.cgi endpoint improperly validates the 'proto' parameter, allowing shell metacharacters or command separators to break out of intended command contexts and execute arbitrary OS commands. CGI-based vulnerabilities in embedded device firmware are particularly severe because the web server often runs with elevated privileges (typically root on consumer routers), and embedded Linux distributions frequently lack modern exploit mitigations like ASLR or stack canaries. The affected CPE (cpe:2.3:a:totolink:a8000ru) identifies the AC2600 wireless router product line running vulnerable firmware version 7.1cu.643_b20200521 released in May 2020.

RemediationAI

No vendor-released patch or firmware update was identified in the provided references. Check the Totolink support site (https://www.totolink.net/) for firmware updates newer than 7.1cu.643_b20200521, though the absence of a security advisory suggests limited vendor response. Immediate compensating controls: (1) Remove A8000RU devices from internet-facing deployments and place behind dedicated firewall appliances - this eliminates remote attack vector but requires network redesign. (2) Implement strict IP-based access control lists (ACLs) permitting admin interface access only from specific management workstations - reduces attack surface but fails if attacker compromises permitted IPs. (3) Disable remote administration entirely via device settings if WAN-side management is not required - effective mitigation but prevents legitimate remote management. (4) Deploy network segmentation isolating IoT/router devices from critical assets - contains post-exploitation lateral movement but does not prevent initial compromise. Long-term solution: replace affected devices with actively supported router models from vendors with documented security update programs.