# CVE-2026-34121: Authentication Bypass in DS Configuration Service via HTTP Request Parsing Differential of TP-Link Tapo C520WS and C210

Status: published. Published: 2026-04-02. Updated: 2026-11-02.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: TPLink) — https://www.tp-link.com/us/support/download/tapo-c520ws/#Firmware-Release-Notes
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: TPLink) — https://www.tp-link.com/en/support/download/tapo-c520ws/#Firmware-Release-Notes
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: TPLink) — https://www.tp-link.com/us/support/download/tapo-c210/v3.60/#Firmware-Release-Notes

## Affected products and versions

- TP-Link Systems Inc. / Tapo C520WS v2.6: ≥ 0; < 1.2.4 Build 260326 Rel.24666n (affected, custom). Source: CNA: TPLink
- TP Link Systems Inc. / Tapo C210 v3.6: ≥ 0; < 1.2.7 Build 260818 Rel.64715n (affected, custom). Source: CNA: TPLink

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:tp-link:tapo_c520ws_firmware:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "1.2.4",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      },
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:h:tp-link:tapo_c520ws:2.6:*:*:*:*:*:*:*",
            "vulnerable": false
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "AND"
  }
]
```

## Severity and prioritization

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N; source: CNA: TPLink

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/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; source: NVD: f23511db-6c3e-4e32-a477-6aa17d310630

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: NVD: nvd@nist.gov

- CISA KEV: No listing in collected sources

- EPSS: 0.47% as of 2026-11-02; percentile 40.59%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-287

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.tp-link.com/us/support/download/tapo-c520ws/#Firmware-Release-Notes (CNA: TPLink; patch)

- https://www.tp-link.com/en/support/download/tapo-c520ws/#Firmware-Release-Notes (CNA: TPLink; patch)

- https://www.tp-link.com/us/support/faq/5047/ (CNA: TPLink; vendor-advisory)

- https://www.tp-link.com/us/support/download/tapo-c210/v3.60/#Firmware-Release-Notes (CNA: TPLink; patch)

- https://www.tp-link.com/en/support/download/tapo-c520ws/#Firmware-Release-Notes (f23511db-6c3e-4e32-a477-6aa17d310630; Release Notes)

- https://www.tp-link.com/us/support/download/tapo-c210/v3.60/#Firmware-Release-Notes (f23511db-6c3e-4e32-a477-6aa17d310630)

- https://www.tp-link.com/us/support/download/tapo-c520ws/#Firmware-Release-Notes (f23511db-6c3e-4e32-a477-6aa17d310630; Release Notes)

- https://www.tp-link.com/us/support/faq/5047/ (f23511db-6c3e-4e32-a477-6aa17d310630; Vendor Advisory)

## Provenance

- CNA: TPLink: https://www.cve.org/CVERecord?id=CVE-2026-34121; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34121; retrieved 2026-11-03; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-34121; retrieved 2026-11-02; source updated Not reported

Revision: 26734ee303d8d9adde570f6edd9bf8304a0868b236a9af3b39d20aa24b5e12c5

Canonical: https://y2.dev/cve/CVE-2026-34121

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