T6: Improper Authentication
CVE-2025-6916 is a high-severity improper authentication vulnerability in T6 from TOTOLINK, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected T6 versions: 4.1.5cu.748_B20211015. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.89% chance of exploitation within 30 days, higher than 60% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of T6 you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TOTOLINK | T6 | 4.1.5cu.748_B20211015 | Not stated |
| TOTOLINK | T6 Firmware | v4.1.5cu.748_b20211015 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vuldb.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.4 | High | CNA (vuldb.com) |
| CVSS 3.1 | 8.8 | High | CNA (vuldb.com) |
| CVSS 2.0 | 8.3 | High | CNA (vuldb.com) |
Official description
A vulnerability, which was classified as critical, was found in TOTOLINK T6 4.1.5cu.748_B20211015. This affects the function Form_Login of the file /formLoginAuth.htm. The manipulation of the argument authCode/goURL leads to missing authentication. The attack needs to be initiated within the local network. The exploit has been disclosed to the public and may be used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How developers prevent this class of flaw
- Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vuldb.com/?ctiid.314409Permissions Required, Third Party Advisory, VDB Entry
- vuldb.com/?id.314409Third Party Advisory, VDB Entry
- vuldb.com/?submit.605101Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- github.com/c0nyy/IoT_vuln/blob/main/TOTOLINK%20T6%20Vuln.mdExploit, Third Party Advisory
Other references
- totolink.net/Product
Other vulnerabilities in T6
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
Recent Improper Authentication vulnerabilities
- 9.6 Critical severity
- 8.8 High severity
- 10.0 Critical severity
- 9.6 Critical severity
- 9.8 Critical severity
- 10.0 Critical severity
Spotted an error? Tell us.