CVE-2021-20121Public exploit

Authenticated file disclosure via UPnP symlink following

Published Oct 11, 2021 · Updated Aug 3, 2024

Arbitrary file read in TELUS Wi-Fi Hub firmware 3.00.20 allows physically proximate attackers with authenticated access to read device files via USB. The DLNA/UPnP media server follows a crafted .wav symbolic link on an attached drive and serves the link target after crafted share-path requests. Physical USB insertion and a valid web-interface session are required; exploitation discloses otherwise inaccessible local files without modifying them.

CVSS severity4.0
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file read in TELUS Wi-Fi Hub firmware 3.00.20 allows physically proximate attackers with authenticated access to read device files via USB. The DLNA/UPnP media server follows a crafted .wav symbolic link on an attached drive and serves the link target after crafted share-path requests. Physical USB insertion and a valid web-interface session are required; exploitation discloses otherwise inaccessible local files without modifying them.

The record

CVE
CVE-2021-20121
Published
Oct 11, 2021
Updated
Aug 3, 2024
Vendor
TELUS
Product
TELUS Wi-Fi Hub
Classifications
T1005
Attack vector
physical
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 11, 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=3.00.20

What conditions does exploitation require?

Attack vectorphysical
Required privilegesauthenticated

What is affected?

TELUS · TELUS Wi-Fi Hubversion=3.00.20

Published CVSS scores

4.0NVDCVSS:3.1/AV:P/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0TenableCVSS:3.0/AV:P/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
1.9NVDAV:L/AC:M/Au:N/C:P/I:N/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1005Data from Local System

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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