CVE-2021-42849: A weak default password for the serial port was reported in some Lenovo Personal Cloud Storage devices that co
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Routine
MEDIUM 6.8UPGRADEUPGRADEUPGRADE
CVE-2021-42849 is a medium-severity flaw (CVSS 6.8) affecting a1 firmware, t1 firmware, x1 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A weak default password for the serial port was reported in some Lenovo Personal Cloud Storage devices that could allow unauthorized device access to an attacker with physical access.
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
lenovo a1 firmware UPGRADE
Affected: < 5.3.6.a1
Fixed in: 5.3.6.a1
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.
lenovo t1 firmware UPGRADE
Affected: < 5.3.6.t1
Fixed in: 5.3.6.t1
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.
lenovo x1 firmware UPGRADE
Affected: < 5.3.8.x1
Fixed in: 5.3.8.x1
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.
lenovo t2 firmware UPGRADE
Affected: < 5.3.8.t2
Fixed in: 5.3.8.t2
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.
lenovo t2pro firmware UPGRADE
Affected: < 5.3.7.t2-pro
Fixed in: 5.3.7.t2-pro
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.
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-2021-42849?
a1 firmware: upgrade to 5.3.6.a1; t1 firmware: upgrade to 5.3.6.t1; x1 firmware: upgrade to 5.3.8.x1. Exact commands for each OS are on this page.
Is CVE-2021-42849 being exploited?
CVE-2021-42849 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-2021-42849 affect?
CVE-2021-42849 affects a1 firmware, t1 firmware, x1 firmware. Severity is medium (CVSS 6.8). A weak default password for the serial port was reported in some Lenovo Personal Cloud Storage devices that could allow unauthorized device access to an attacker with physical access.
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