Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2001-0537

IOS

Cisco / IOS

Watch CVE-2001-0537 Browse KEV feed
Severity
CVSS 9.3 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
68.5%
First observed
02 Jul 2026
Last observed
07 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2001-0537 is an unauthenticated vulnerability affecting Cisco IOS. HTTP server for Cisco IOS 11.3 to 12.2 allows attackers to bypass authentication and execute arbitrary commands, when local authorization is being...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Also confirmed by third-party sources.

Who is affected?

Cisco / IOS.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

IOS

HTTP server for Cisco IOS 11.3 to 12.2 allows attackers to bypass authentication and execute arbitrary commands, when local authorization is being used, by specifying a high access level in the URL.

View vendor advisory (opens in new tab)
Published
09 Mar 2002
Exploitation Reported
21 Jun 2025
Attack vector
Remote
Complexity
—
Privileges
None
User interaction
—

Tags

nuclei_scanner ios edge

CVE References

Exploitation evidence

Why Previdian 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 21 Jun 2025

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 02 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

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 2025-06-21 00:00 UTC
Previdian Sensors 2026-07-31 10:42 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

127

Attempts observed

13

Unique attacker IPs

8

Attacker countries

BG · DE · JP · NL · PL · SC · US · YE

26

Sensors observed

CVE-2001-0537 exploitation attempts over the last 86 days

Daily events observed by Previdian sensors

Updated 10 Oct 2026

0
2
1
0
0
0
0
0
0
0
0
0
4
2
7
2
3
2
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
2
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
94
1
1
0
0
0
17 Jul 4 Aug 22 Aug 9 Sep 10 Oct

First observed 02 Jul 2026 · Last observed 07 Oct 2026

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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
97
25
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 →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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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/2001/CVE-2001-0537.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v2.0

9.3 High

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

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

EPSS

68.5%

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

Weaknesses

Improper Authentication CWE-287

Potential Proof of Concepts

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

Cisco IOS HTTP Configuration - Authentication Bypass

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 13:29 UTC

    Indicators of compromise added (18)

    Indicators of compromise recorded

  2. 13:29 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 14:19 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 00:00 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  5. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  6. 05:00 UTC

    CVE published

    Vulnerability disclosed publicly

  7. 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.

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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-2001-0537

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2001-0537",
  "confidence": "Confirmed",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.6845,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 127, "sensors": 26 }
}