CVE-2020-25366: An issue in the component /cgi-bin/upload_firmware.cgi of D-Link DIR-823G REVA1 1.02B05 allows attackers to ca

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CRITICAL 9.1REMOTEMITIGATE

CVE-2020-25366 is a critical-severity flaw (CVSS 9.1) affecting dir-823g firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue in the component /cgi-bin/upload_firmware.cgi of D-Link DIR-823G REVA1 1.02B05 allows attackers to cause a denial of service (DoS) via unspecified vectors.

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	9.1 (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-862
Published	2021-11-04
Last modified	2026-07-09

Publisher (CNA): MITRE · Vendor: dlink

Last updated 2026-07-09 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-11-04 11:15 UTCPublished CVE record published
2026-07-09 00:17 UTCUpdated Record last modified

dlink dir-823g firmware MITIGATE

Affected: 1.02b05

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.02b05

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-2020-25366?

dir-823g firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-25366 being exploited?

CVE-2020-25366 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-2020-25366 affect?

CVE-2020-25366 affects dir-823g firmware. Severity is critical (CVSS 9.1). An issue in the component /cgi-bin/upload_firmware.cgi of D-Link DIR-823G REVA1 1.02B05 allows attackers to cause a denial of service (DoS) via unspecified vectors.

How urgent is CVE-2020-25366?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

D-Link vulnerabilities

Related CVEs

CVE-2026-15270 HIGH 7.5 MITIGATE A weakness has been identified in D-link DIR-823G 1.0.2B05_20181207
CVE-2026-11492 MEDIUM 4.3 MITIGATE A security flaw has been discovered in D-Link DIR-823G 1.0.2B05
CVE-2020-25368 CRITICAL 9.8 MITIGATE A command injection vulnerability was discovered in the HNAP1 protocol in D-Link DIR-823G devices with firmwar
CVE-2020-25367 CRITICAL 9.8 MITIGATE A command injection vulnerability was discovered in the HNAP1 protocol in D-Link DIR-823G devices with firmwar
CVE-2025-60675 MEDIUM 5.4 MITIGATE A command injection vulnerability exists in the D-Link DIR-823G router firmware DIR823G_V1.0.2B05_20181207.bin

References

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