CVE-2021-20133

Authenticated file disclosure via MOTD path traversal

Published Dec 30, 2021 · Updated Aug 3, 2024

Absolute path traversal in Quagga Services on D-Link DIR-2640 1.11B02 and earlier allows remote authenticated attackers to read files. The Quagga command-line interface accepts an attacker-controlled message-of-the-day path and reads that file, while virtual paths such as /dev/urandom can hang or disrupt the zebra and ripd services. Access requires authentication to the adjacent-network Quagga interface; exposed files can include credentials, keys, and configuration data, with service interruption also possible.

CVSS severity6.1
Medium
EPSS probability2.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Absolute path traversal in Quagga Services on D-Link DIR-2640 1.11B02 and earlier allows remote authenticated attackers to read files. The Quagga command-line interface accepts an attacker-controlled message-of-the-day path and reads that file, while virtual paths such as /dev/urandom can hang or disrupt the zebra and ripd services. Access requires authentication to the adjacent-network Quagga interface; exposed files can include credentials, keys, and configuration data, with service interruption also possible.

The record

CVE
CVE-2021-20133
Published
Dec 30, 2021
Updated
Aug 3, 2024
Vendor
D-Link
Product
DIR-2640
Classifications
CWE-22, T1190
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

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

  1. Affected versionversion=<= 1.11B02

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

D-Link · DIR-2640version=<= 1.11B02

Published CVSS scores

7.1NVDAV:A/AC:L/Au:S/C:C/I:N/A:C
6.1NVDCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:N/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.

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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)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Path Traversal
T1190Exploit Public-Facing Application

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

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Your stack

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