Vulnerability report

Exploitation attempts observed in the wild High confidence Not in CISA KEV

CVE-2021-21745

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

Watch CVE-2021-21745 Browse KEV feed
Severity
CVSS 4.3 · Medium
Confidence
High
Exploit status
Exploitation attempts observed 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...

Have exploitation attempts been observed?

Yes. Exploitation attempts have been reported for this vulnerability. Previdian lists it as a known exploited vulnerability. Also reported by third-party sources. 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.

n/a Affected
MF971R
BD_ZTE_MF971RV1.0.0B05, BD_PLKPLMF971R1V1.0.0B06, BD_MF971R2V1.0.0B03, BD_ZTE_MF971RS2V1.0.0B03, BD_ZTE_MF971RSV1.0.0B05
Published
20 Oct 2021
Exploitation Attempts Reported
20 Oct 2021
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
Required

Tags

nuclei_scanner

CVE References

Exploitation evidence

Evidence of exploitation attempts

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

Exploitation attempts observed in the wild

The Shadowserver

Recorded 20 Oct 2021

A trusted third party reported exploitation attempts.

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 Previdian Pro API.

Learn about Pro API access
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
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

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

Learn about virtual patches →

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

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

55.7%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

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 attempts

  1. 14:20 UTC

    Public PoC available

    Public proof-of-concept code published

  2. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  3. 15:20 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party report of exploitation attempts

  4. 15:20 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • 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

Sample API response 
{
  "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 }
}