What is the CVSS score of CVE-2026-51661?

CVE-2026-51661 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.2%.

Which versions of TOTOLINK T6 are affected by CVE-2026-51661?

TOTOLINK T6 routers (firmware 4.1.5cu.748_B20211015 and earlier) expose internal network topology-host IP addresses, service ports, and NAT configurations-to remote unauthenticated attackers.

How to fix or mitigate CVE-2026-51661?

Within 24 hours, inventory all TOTOLINK T6 routers in your environment and document firmware versions and network scope. Within 7 days, implement network controls: disable remote management access, apply firewall rules to restrict WAN connectivity to the management interface, isolate router administrative access to trusted IP ranges, and segment the router from critical systems using network ACLs. Within 30 days, subscribe to TOTOLINK security advisories for firmware updates (monitor for versions after 4.1.5cu.748_B20211015), establish a hardware replacement plan if vendor patches are delayed, and conduct quarterly audits of router configuration and access logs to detect unauthorized getPortForwardRules API calls.

TOTOLINK T6 CVE-2026-51661

EUVD-2026-68007 CRITICAL

Improper Access Control (CWE-284)

2026-08-28 mitre

GHSA-24g8-x36j-cf39

Authentication Bypass

9.1

CVSS 3.1 · Vendor: mitre

Severity by source

Vendor (mitre) PRIMARY

9.1 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

vuln.today AI

5.3 MEDIUM

Unauthenticated network read of port-forward rules gives limited confidentiality (C:L) with no modification (I:N) or availability impact, contra the input's C:H/I:H.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Metadata Corrected

Sep 01, 2026 - 21:40 vuln.today

tag: N A removed

Analysis Generated

Sep 01, 2026 - 20:41 vuln.today

CVSS changed

Sep 01, 2026 - 18:22 NVD

9.1 (CRITICAL)

CVE Published

Aug 28, 2026 - 00:00 cve.org

CRITICAL 9.1

CVE Published

Aug 28, 2026 - 00:00 cve.org

UNKNOWN (no severity yet)

DescriptionCVE.org

Incorrect access control in the getPortForwardRules function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain port-forwarding rules via sending a crafted POST request to /cgi-bin/cstecgi.cgi.

AnalysisAI

Information disclosure in the TOTOLINK T6 router (firmware 4.1.5cu.748_B20211015) lets remote unauthenticated attackers retrieve the device's port-forwarding rules by sending a crafted POST request to the getPortForwardRules handler at /cgi-bin/cstecgi.cgi. The endpoint enforces no authentication (CWE-284), exposing internal host IPs, service ports, and NAT mappings that aid downstream targeting. …

Unlock full vulnerability intelligence

Risk assessment & exploitation conditions
Attack chain visualization
Remediation with exact patch versions
Threat intelligence from 22 sources
Personal watchlist & email alerts

Continue with Google Continue with GitHub

Free forever · No credit card required

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

technique details hidden

Delivery

technique details hidden

Exploit

technique details hidden

Execution

technique details hidden

Impact

technique details hidden

Access

technique details hidden

Delivery

technique details hidden

Exploit

technique details hidden

Execution

technique details hidden

Impact

technique details hidden

Vulnerability AssessmentAI

Exploitation	Exploitation requires network reachability to the TOTOLINK T6 web management service and the ability to send a POST request to /cgi-bin/cstecgi.cgi invoking the getPortForwardRules function; no authentication, credentials, or user interaction are needed (PR:N/UI:N). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	Signals conflict on severity. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation	No vendor-released patch version is identified at time of analysis; the referenced links are vendor/download and coordination pages, not a tagged fixed build, so monitor https://www.totolink.net/ and the TOTOLINK coordination README for a firmware update superseding 4.1.5cu.748_B20211015 and apply it once published. … Detailed patch versions, workarounds, and compensating controls in full report.