CVE-2025-7862Public exploitNetwork attack vector

Remote shell access via unauthenticated Telnet enablement

Published Jul 20, 2025 · Updated Jul 22, 2025

Improper authentication in TOTOLINK T6 firmware 4.1.5cu.748_B20211015 allows remote attackers to obtain a shell via Telnet. The setTelnetCfg handler in /cgi-bin/cstecgi.cgi accepts an unauthenticated HTTP POST or MQTT message setting telnet_enabled to 1, which starts the Telnet service. Network reachability to the router's HTTP interface or MQTT port 1883 is sufficient to enable Telnet and expose remote shell access without an existing account.

CVSS severity9.8
Critical
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in TOTOLINK T6 firmware 4.1.5cu.748_B20211015 allows remote attackers to obtain a shell via Telnet. The setTelnetCfg handler in /cgi-bin/cstecgi.cgi accepts an unauthenticated HTTP POST or MQTT message setting telnet_enabled to 1, which starts the Telnet service. Network reachability to the router's HTTP interface or MQTT port 1883 is sufficient to enable Telnet and expose remote shell access without an existing account.

The record

CVE
CVE-2025-7862
Published
Jul 20, 2025
Updated
Jul 22, 2025
Vendor
TOTOLINK
Product
T6
Classifications
CWE-306, CWE-287, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.1.5cu.748_B20211015

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TOTOLINK · T6version=4.1.5cu.748_B20211015

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.5VulDB CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/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
7.5VulDB CNAAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3VulDB CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
CWE-287Improper Authentication
T1210Exploitation of Remote Services

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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