Tapo C520WS v2.6: Improper Authentication
CVE-2026-34121 is a high-severity improper authentication vulnerability in Tapo C520WS v2.6 from TP-Link, 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. The record lists version 1.2.4 Build 260326 Rel.24666n as the first without the flaw, so updating Tapo C520WS v2.6 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.47% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Tapo C520WS v2.6 to 1.2.4 Build 260326 Rel.24666n or a later version.
- Update Tapo C210 v3.6 to 1.2.7 Build 260818 Rel.64715n or a later version.
- Update Tapo C520ws Firmware to 1.2.4 or a later version.
- Read the advisory on tp-link.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | Tapo C520WS v2.6 | before 1.2.4 Build 260326 Rel.24666n | 1.2.4 Build 260326 Rel.24666n |
| TP-Link | Tapo C210 v3.6 | before 1.2.7 Build 260818 Rel.64715n | 1.2.7 Build 260818 Rel.64715n |
| TP-Link | Tapo C520ws Firmware | before 1.2.4 | 1.2.4 |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
An authentication bypass vulnerability within the HTTP handling of the DS configuration service in TP-Link Tapo C520WS v2.6 and C210 v3 was identified, due to inconsistent parsing and authorization logic in JSON requests during authentication check. An unauthenticated attacker can append an authentication-exempt action to a request containing privileged DS do actions, bypassing authorization checks. Successful exploitation allows unauthenticated execution of restricted configuration actions, which may result in unauthorized modification of device state.
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: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Other vulnerabilities in Tapo C520WS v2.6
- 7.8 High severity
Recent Improper Authentication vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.3 High severity
- 9.8 Critical severity
- 8.2 High severity
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