CVE-2021-33903Public exploitNetwork attack vector

Root access via stale SNMPv3 credentials

Published Oct 7, 2021 · Updated Aug 4, 2024

Incorrect access control in LANCOM LCOS 10.40 through 10.42.0473-RU3 allows remote authenticated users to retain SNMPv3 root access. The passwd -n CLI path changes the device root password without synchronizing the credential used by the SNMPv3 service. Exploitation requires SNMPv3 to be enabled and knowledge of the previous root password, which continues to authorize reading and changing device data.

CVSS severity8.8
High
EPSS probability1.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect access control in LANCOM LCOS 10.40 through 10.42.0473-RU3 allows remote authenticated users to retain SNMPv3 root access. The passwd -n CLI path changes the device root password without synchronizing the credential used by the SNMPv3 service. Exploitation requires SNMPv3 to be enabled and knowledge of the previous root password, which continues to authorize reading and changing device data.

The record

CVE
CVE-2021-33903
Published
Oct 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

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

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.5NIST NVDAV:N/AC:M/Au:S/C:C/I:C/A:C
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1078Valid Accounts

Public exploit references

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

Technologies

Your stack

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Your stack

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