CVE-2021-34204Public exploit

Root access via plaintext device credentials

Published Jun 16, 2021 · Updated Jul 9, 2026

Credential exposure in D-Link DIR-2640-US 1.01B04 allows physically proximate attackers to obtain root access through the serial port. The /sbin/storage.sh script reads administrative values from NVRAM and writes a UID 0 account to /etc/passwd, while RT2860_default_vlan stores the device credentials in plaintext. Physical access to the serial console is required; the recovered credentials provide control over the router and its data.

CVSS severity6.8
Medium
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Credential exposure in D-Link DIR-2640-US 1.01B04 allows physically proximate attackers to obtain root access through the serial port. The /sbin/storage.sh script reads administrative values from NVRAM and writes a UID 0 account to /etc/passwd, while RT2860_default_vlan stores the device credentials in plaintext. Physical access to the serial console is required; the recovered credentials provide control over the router and its data.

The record

CVE
CVE-2021-34204
Published
Jun 16, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-522, T1552.001
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record 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 vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.6secnotesCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
6.8INCIBE-CERTCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.2INCIBE-CERTAV:L/AC:L/Au:N/C:C/I:C/A:C

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.

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No observations available

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

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
T1552.001Credentials In Files

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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