CVE-2021-4242: A vulnerability was found in Sapido BR270n, BRC76n, GR297 and RB1732 and classified as critical
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MEDIUM 6.3MITIGATEMITIGATEMITIGATE
CVE-2021-4242 is a medium-severity flaw (CVSS 6.3) affecting br270n firmware, brc76n firmware, gr297n firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A vulnerability was found in Sapido BR270n, BRC76n, GR297 and RB1732 and classified as critical. Affected by this issue is some unknown functionality of the file ip/syscmd.htm. The manipulation leads to os command injection. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-214592.
Why this priority
Public exploit reference
No fix is published yet: follow the downgrade or mitigation steps.
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
Published CVE record published
Updated Record last modified
sapido br270n firmware MITIGATE
Affected: 2.1.03
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.1.03
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.
sapido brc76n firmware MITIGATE
Affected: 2.1.03
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.1.03
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.
sapido gr297n firmware MITIGATE
Affected: 2.1.3
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.1.3
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.
sapido rb-1732 firmware MITIGATE
Affected: 2.0.43
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.0.43
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 sourceNVD · 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-2021-4242?
br270n firmware: mitigate or apply the listed mitigation; brc76n firmware: mitigate or apply the listed mitigation; gr297n firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2021-4242 being exploited?
CVE-2021-4242 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-2021-4242 affect?
CVE-2021-4242 affects br270n firmware, brc76n firmware, gr297n firmware. Severity is medium (CVSS 6.3). A vulnerability was found in Sapido BR270n, BRC76n, GR297 and RB1732 and classified as critical. Affected by this issue is some unknown functionality of the file ip/syscmd.htm. The manipulation leads to os command injection. The attack may
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