CVE-2021-34795Network attack vector

Unauthenticated device takeover via static debugging credential

Published Nov 4, 2021 · Updated Nov 7, 2024

Authentication bypass in Cisco Catalyst PON Series Switches ONT allows remote attackers to gain complete device control over Telnet. The Telnet service retains an unintentional debugging account with a default static password and accepts that credential for login. Exposure requires Telnet to be enabled, a non-default configuration, and access through a LAN port unless remote management is enabled.

CVSS severity10.0
Critical
EPSS probability1.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Cisco Catalyst PON Series Switches ONT allows remote attackers to gain complete device control over Telnet. The Telnet service retains an unintentional debugging account with a default static password and accepts that credential for login. Exposure requires Telnet to be enabled, a non-default configuration, and access through a LAN port unless remote management is enabled.

The record

CVE
CVE-2021-34795
Published
Nov 4, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Catalyst PON Series Switches
Classifications
CWE-1188, CWE-284, T1078.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Catalyst PON Series Switchesversion=n/a

Published CVSS scores

10.0NISTAV:N/AC:L/Au:N/C:C/I:C/A:C
9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1188Insecure Default Initialization of Resource
CWE-284Improper Access Control
T1078.001Default Accounts

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo