CVE-2021-26709: D-Link DSL-320B-D1 devices through EU_1.25 are prone to multiple Stack-Based Buffer Overflows that allow unaut

Q: How do I fix CVE-2021-26709?

dsl-320b-d1: upgrade to newer than eu_1.25. Exact commands for each OS are on this page.

Q: Is CVE-2021-26709 being exploited?

CVE-2021-26709 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-26709 affect?

CVE-2021-26709 affects dsl-320b-d1. Severity is critical (CVSS 9.8). D-Link DSL-320B-D1 devices through EU_1.25 are prone to multiple Stack-Based Buffer Overflows that allow unauthenticated remote attackers to take over a device via the login.xgi user and pass parameters. NOTE: This vulnerability only affect

Q: How urgent is CVE-2021-26709?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-26709 is a critical-severity flaw (CVSS 9.8) affecting dsl-320b-d1. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

D-Link DSL-320B-D1 devices through EU_1.25 are prone to multiple Stack-Based Buffer Overflows that allow unauthenticated remote attackers to take over a device via the login.xgi user and pass parameters. NOTE: This vulnerability only affects products that are no longer supported by the maintainer

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	40.1% (top 1%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-04-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: d-link

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-04-07 11:15 UTCPublished CVE record published
2026-06-17 03:43 UTCUpdated Record last modified

d-link dsl-320b-d1 UPGRADE

Affected: <= eu_1.25

Fixed in: newer than eu_1.25

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · librepo · FIXED · 1.21.3-1.fc46 · FEDORA-2026-c502136ca7 · source

sudo dnf upgrade --advisory=FEDORA-2026-c502136ca7

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-26709?

dsl-320b-d1: upgrade to newer than eu_1.25. Exact commands for each OS are on this page.

Is CVE-2021-26709 being exploited?

CVE-2021-26709 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-26709 affect?

CVE-2021-26709 affects dsl-320b-d1. Severity is critical (CVSS 9.8). D-Link DSL-320B-D1 devices through EU_1.25 are prone to multiple Stack-Based Buffer Overflows that allow unauthenticated remote attackers to take over a device via the login.xgi user and pass parameters. NOTE: This vulnerability only affect

How urgent is CVE-2021-26709?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

D-Link vulnerabilities

References

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