CVE-2021-26709Public exploitNetwork attack vector

Unauthenticated device takeover via login parameter overflows

Published Apr 7, 2021 · Updated Aug 3, 2024

Stack-based buffer overflows in D-Link DSL-320B-D1 firmware EU_1.25 and earlier allow remote attackers to take over the device. Oversized user or pass values supplied to login.xgi exceed the respective stack buffers, with published overwrite offsets of 652 and 641 bytes. No authentication or user interaction is required; successful exploitation executes attacker-supplied code and grants control of the end-of-life modem.

CVSS severity9.8
Critical
EPSS probability40.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflows in D-Link DSL-320B-D1 firmware EU_1.25 and earlier allow remote attackers to take over the device. Oversized user or pass values supplied to login.xgi exceed the respective stack buffers, with published overwrite offsets of 652 and 641 bytes. No authentication or user interaction is required; successful exploitation executes attacker-supplied code and grants control of the end-of-life modem.

The record

CVE
CVE-2021-26709
Published
Apr 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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