CVE-2021-26551: An issue was discovered in SmartFoxServer 2.17.0

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HIGH 8.8DOWNGRADE

CVE-2021-26551 is a high-severity flaw (CVSS 8.8) affecting smartfoxserver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in SmartFoxServer 2.17.0. An attacker can execute arbitrary Python code, and bypass the javashell.py protection mechanism, by creating /config/ConsoleModuleUnlock.txt and editing /config/admin/admintool.xml to enable the Console module.

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	2.6% (top 15%)
CISA exploited list	No
Weakness	CWE-94
Published	2021-02-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: smartfoxserver

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

Am I affected?

Timeline

2021-02-09 20:15 UTCPublished CVE record published
2026-06-17 03:43 UTCUpdated Record last modified

smartfoxserver smartfoxserver DOWNGRADE

Affected: 2.17.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.17.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.17.0 (Debian / Ubuntu)

apt-cache madison smartfoxserver sudo apt install smartfoxserver=<VERSION_BEFORE_2.17.0> sudo apt-mark hold smartfoxserver

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

dnf --showduplicates list smartfoxserver sudo dnf downgrade smartfoxserver-<VERSION_BEFORE_2.17.0> sudo dnf versionlock add smartfoxserver

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-2021-26551?

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

Is CVE-2021-26551 being exploited?

CVE-2021-26551 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-2021-26551 affect?

CVE-2021-26551 affects smartfoxserver. Severity is high (CVSS 8.8). An issue was discovered in SmartFoxServer 2.17.0. An attacker can execute arbitrary Python code, and bypass the javashell.py protection mechanism, by creating /config/ConsoleModuleUnlock.txt and editing /config/admin/admintool.xml to enable

How urgent is CVE-2021-26551?

Priority 57/100. High severity; Public exploit reference

Software pages

Python vulnerabilities

Related CVEs

CVE-2021-26550 MEDIUM 5.5 DOWNGRADE An issue was discovered in SmartFoxServer 2.17.0
CVE-2021-26549 MEDIUM 5.4 DOWNGRADE An XSS issue was discovered in SmartFoxServer 2.17.0

References

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