Is CVE-2021-21745 actively exploited?

Yes. KEV Intelligence tracks CVE-2021-21745 as a known exploited vulnerability. Confidence is high.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2021-21745. Our sensors continue to monitor for activity targeting this CVE.

No. CVE-2021-21745 is not currently listed in CISA KEV.

Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2021-21745

Q: Which versions are affected?

CVE-2021-21745 affects ZTE MF971R. Reported affected version: BD_ZTE_MF971RV1.0.0B05, BD_PLKPLMF971R1V1.0.0B06, BD_MF971R2V1.0.0B03, BD_ZTE_MF971RS2V1.0.0B03, BD_ZTE_MF971RSV1.0.0B05.

MF971R Authentication Bypass

ZTE / MF971R · BD_ZTE_MF971RV1.0.0B05, BD_PLKPLMF971R1V1.0.0B06, BD_MF971R2V1.0.0B03, BD_ZTE_MF971RS2V1.0.0B03, BD_ZTE_MF971RSV1.0.0B05

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Severity: CVSS 4.3 · Medium
Confidence: High
Exploit status: Exploited in the wild
EPSS: 55.7%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-21745 is an unauthenticated vulnerability affecting ZTE MF971R. ZTE MF971R product has a Referer authentication bypass vulnerability. Without CSRF verification, an attackercould use this vulnerability to...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is high.

Who is affected?

ZTE / MF971R bd_zte_mf971rv1.0.0b05, bd_plkplmf971r1v1.0.0b06, bd_mf971r2v1.0.0b03, bd_zte_mf971rs2v1.0.0b03, bd_zte_mf971rsv1.0.0b05.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

ZTE MF971R product has a Referer authentication bypass vulnerability

ZTE MF971R product has a Referer authentication bypass vulnerability.

Without CSRF verification, an attackercould use this vulnerability to perform illegal authorization operations by sending a request to the user to click.

Vendor Product Affected Status

n/a MF971R BD_ZTE_MF971RV1.0.0B05, BD_PLKPLMF971R1V1.0.0B06, BD_MF971R2V1.0.0B03, BD_ZTE_MF971RS2V1.0.0B03, BD_ZTE_MF971RSV1.0.0B05 Affected

Published: 20 Oct 2021
Exploitation Reported: 20 Oct 2021
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: Required

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-21745
support.zte.com.cn/support/news/LoopholeInfoDetail.aspx support.zte.com.cn · CVE Record https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsI...

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

The Shadowserver

Recorded 20 Oct 2021

Independent exploitation attestation added to the KEV Intelligence record.

Proof of concept available

Nuclei Templates

Recorded 12 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source	Added
The Shadowserver First	2021-10-20 15:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

Nuclei template detected 25 Apr 2025.

View Nuclei template

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

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Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner	Reference	Detected
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21745.yaml	25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

4.3 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

EPSS

55.7%

Weaknesses

Cross-Site Request Forgery (CSRF) CWE-352

All CVSS Scores

CVSS v3.1 4.3 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS v2.0 4.3 Medium

AV:N/AC:M/Au:N/C:N/I:P/A:N

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

ZTE MF971R - Referer authentication bypass

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

12 Jun 2026
Public PoC available

Public proof-of-concept code published
25 Apr 2025
Nuclei template available

Scanner coverage available
20 Oct 2021
Added to KEV Intelligence KEV Feed

High-confidence, third-party attested exploitation
20 Oct 2021
CVE published

Vulnerability disclosed publicly
04 Jan 2021
CVE ID reserved

Identifier reserved by the CNA

Pro API

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-21745

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-21745",
  "confidence": "High",
  "cvss_score": 4.3,
  "cvss_estimated": false,
  "epss_score": 0.55709,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

Early warning alerts

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