CVE-2020-9277: An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices

This week

CRITICAL 9.8REMOTEMITIGATE

CVE-2020-9277 is a critical-severity flaw (CVSS 9.8) affecting dsl-2640b firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices. Authentication can be bypassed when accessing cgi modules. This allows one to perform administrative tasks (e.g., modify the admin password) with no authentication.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 16%)
CISA exploited list	No
Weakness	CWE-287
Published	2020-04-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: dlink

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

Am I affected?

Timeline

2020-04-20 23:15 UTCPublished CVE record published
2026-06-17 03:27 UTCUpdated Record last modified

dlink dsl-2640b firmware MITIGATE

Affected: eu_4.01b

Fixed in: no fixed release known

Safe to downgrade to: a release before eu_4.01b

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.

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-2020-9277?

dsl-2640b firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-9277 being exploited?

CVE-2020-9277 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-2020-9277 affect?

CVE-2020-9277 affects dsl-2640b firmware. Severity is critical (CVSS 9.8). An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices. Authentication can be bypassed when accessing cgi modules. This allows one to perform administrative tasks (e.g., modify the admin password) with no authentication.

How urgent is CVE-2020-9277?

Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

D-Link vulnerabilities

Related CVEs

CVE-2020-9544 HIGH 7.5 MITIGATE An issue was discovered on D-Link DSL-2640B E1 EU_1.01 devices
CVE-2020-9279 CRITICAL 9.8 MITIGATE An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices
CVE-2020-9278 CRITICAL 9.1 MITIGATE An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices
CVE-2020-9276 HIGH 8.8 MITIGATE An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices
CVE-2020-9275 CRITICAL 9.8 MITIGATE An issue was discovered on D-Link DSL-2640B B2 EU_4.01B devices

References

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