CVE-2021-39273: In XeroSecurity Sn1per 9.0 (free version), insecure permissions (0777) are set upon application execution, all

This month

HIGH 8.8DOWNGRADE

CVE-2021-39273 is a high-severity flaw (CVSS 8.8) affecting sn1per. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In XeroSecurity Sn1per 9.0 (free version), insecure permissions (0777) are set upon application execution, allowing an unprivileged user to modify the application, modules, and configuration files. This leads to arbitrary code execution with root privileges.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.7% (top 14%)
CISA exploited list	No
Weakness	CWE-276
Published	2021-08-19
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: xerosecurity

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

Am I affected?

Timeline

2021-08-19 12:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

xerosecurity sn1per DOWNGRADE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

1. Check installed version

apt-cache policy sn1per || rpm -q sn1per || sn1per --version

2. No fixed release: DOWNGRADE to a release before 9.0 (Debian / Ubuntu)

apt-cache madison sn1per sudo apt install sn1per=<VERSION_BEFORE_9.0> sudo apt-mark hold sn1per

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sn1per sudo dnf downgrade sn1per-<VERSION_BEFORE_9.0> sudo dnf versionlock add sn1per

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2021-39273?

sn1per: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-39273 being exploited?

CVE-2021-39273 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-2021-39273 affect?

CVE-2021-39273 affects sn1per. Severity is high (CVSS 8.8). In XeroSecurity Sn1per 9.0 (free version), insecure permissions (0777) are set upon application execution, allowing an unprivileged user to modify the application, modules, and configuration files. This leads to arbitrary code execution wit

How urgent is CVE-2021-39273?

Priority 57/100. High severity; Public exploit reference

Related CVEs

CVE-2021-39274 CRITICAL 9.8 DOWNGRADE In XeroSecurity Sn1per 9.0 (free version), insecure directory permissions (0777) are set during installation,

References

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