CVE-2021-39392: The management tool in MyLittleBackup up to and including 1.7 allows remote attackers to execute arbitrary cod

Q: How do I fix CVE-2021-39392?

mylittlebackup: upgrade to newer than 1.7. Exact commands for each OS are on this page.

Q: Is CVE-2021-39392 being exploited?

CVE-2021-39392 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-2021-39392 affect?

CVE-2021-39392 affects mylittlebackup. Severity is critical (CVSS 9.8). The management tool in MyLittleBackup up to and including 1.7 allows remote attackers to execute arbitrary code because machineKey is hardcoded (the same for all customers' installations) in web.config, and can be used to send serialized AS

Q: How urgent is CVE-2021-39392?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-39392 is a critical-severity flaw (CVSS 9.8) affecting mylittlebackup. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The management tool in MyLittleBackup up to and including 1.7 allows remote attackers to execute arbitrary code because machineKey is hardcoded (the same for all customers' installations) in web.config, and can be used to send serialized ASP code.

Why this priority

Critical severity
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	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-502
Published	2021-09-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mylittletools

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

Am I affected?

Timeline

2021-09-15 17:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

mylittletools mylittlebackup UPGRADE

Affected: <= 1.7

Fixed in: newer than 1.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mylittlebackup || rpm -q mylittlebackup || mylittlebackup --version

2. UPGRADE to newer than 1.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mylittlebackup

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mylittlebackup

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-39392?

mylittlebackup: upgrade to newer than 1.7. Exact commands for each OS are on this page.

Is CVE-2021-39392 being exploited?

CVE-2021-39392 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-2021-39392 affect?

CVE-2021-39392 affects mylittlebackup. Severity is critical (CVSS 9.8). The management tool in MyLittleBackup up to and including 1.7 allows remote attackers to execute arbitrary code because machineKey is hardcoded (the same for all customers' installations) in web.config, and can be used to send serialized AS

How urgent is CVE-2021-39392?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

References

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