CVE-2021-3707Public exploit

Configuration takeover via anonymous TFTP file writes

Published Aug 16, 2021 · Updated Aug 3, 2024

Unauthorized configuration modification in D-Link DSL-2750U firmware ME1.16 and earlier allows remote attackers on the LAN to alter router settings. The TFTP service on UDP port 69 permits anonymous retrieval and replacement of cfg.xml and image.img, and the router accepts a replaced configuration and reboots with its settings. Local-network access is required; replacing cfg.xml can establish attacker-chosen administrative credentials and enable a separate command-injection flaw.

CVSS severity8.8
High
EPSS probability1.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unauthorized configuration modification in D-Link DSL-2750U firmware ME1.16 and earlier allows remote attackers on the LAN to alter router settings. The TFTP service on UDP port 69 permits anonymous retrieval and replacement of cfg.xml and image.img, and the router accepts a replaced configuration and reboots with its settings. Local-network access is required; replacing cfg.xml can establish attacker-chosen administrative credentials and enable a separate command-injection flaw.

The record

CVE
CVE-2021-3707
Published
Aug 16, 2021
Updated
Aug 3, 2024
Vendor
D-Link
Product
DSL-2750U
Classifications
CWE-15, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 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=firmware vME1.16 or prior versions

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

D-Link · DSL-2750Uversion=firmware vME1.16 or prior versions

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:P/A:N
8.8JPCERT/CCCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.3JPCERT/CCAV:A/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-15External Control of System or Configuration Setting
T1210Exploitation of Remote Services

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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