Security readout for executives and security teams
Plain-English summary
A missing access-control check in TOTOLINK T6 firmware 4.1.5cu.748_B20211015 may let an unauthenticated network attacker send a crafted MQTT message that clears device-pairing state and reboots the router. This could disrupt connectivity and require administrative recovery. The supplied evidence does not establish broader affected versions or confirmed real-world exploitation.
Executive priority
Treat as urgent where the exact firmware is deployed and MQTT handling is reachable from untrusted networks. Immediately identify affected devices, reduce broker exposure, and seek vendor-supported remediation. Prioritize connectivity-critical locations because successful abuse can reboot devices and disrupt service. Do not claim an active campaign based on the supplied evidence.
Technical view
CVE-2026-51767 is a CWE-284 issue in recvClearPairCfg within the cs_broker component. A crafted MQTT message can invoke pairing-state reset and reboot behavior without authentication. It carries CVSS 3.1 score 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), although the supplied description directly demonstrates integrity and availability effects, not the scored confidentiality impact.
Likely exposure
Confirmed scope is limited to TOTOLINK T6 firmware 4.1.5cu.748_B20211015. Practical exposure depends on whether an attacker can reach the device's MQTT-handling cs_broker component. The bundle's structured affected-product fields are incomplete, so other models or firmware versions should not be assumed vulnerable.
Exploitation context
The flaw reportedly requires no credentials or user interaction and has low attack complexity over a network path. However, the source bundle marks it absent from KEV and provides no evidence of exploitation in the wild. Public coordination references exist, but the supplied information does not identify exploit maturity, observed campaigns, or a vendor fix.
Researcher notes
The record identifies the vulnerable function and message path but omits complete affected-product metadata, broker reachability conditions, fix status, and evidence supporting confidentiality impact. Assessment should distinguish the described reset-and-reboot behavior from the full CVSS consequences. Coordinate validation carefully because testing may interrupt service or erase pairing state.
Mitigation direction
- Inventory TOTOLINK T6 devices and prioritize those running firmware 4.1.5cu.748_B20211015.
- Check TOTOLINK guidance for fixed firmware or an approved mitigation; no fix is named in the supplied evidence.
- Restrict untrusted network access to MQTT and cs_broker interfaces using existing network controls.
- Segment affected devices and limit their management or broker communication to authorized systems.
- Consider replacement if affected devices lack vendor-supported remediation.
Validation and detection
- Confirm each device's model and installed firmware through trusted inventory or administrative records.
- Review network controls to determine who can reach MQTT services associated with cs_broker.
- Examine logs and monitoring for unexplained reboots, pairing resets, or unusual MQTT traffic.
- Verify any installed update against TOTOLINK's published firmware information.
- Perform disruptive security testing only in an isolated lab, not on production routers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-284: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-51767 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://www.totolink.net/home/menu/detail/menu_listtpl/download/id/190/ids/36.htmlCVE reference, mitre
- https://www.totolink.net/CVE reference, mitre
- https://github.com/DarkBoulder/CVE-Vendor-Coordination/blob/main/TOTOLINK/README.mdCVE reference, mitre
- https://github.com/ShengWu00/CVE-Vendor-Coordination/blob/main/TOTOLINK/README.mdCVE reference, mitre
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Access Control
Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.