CVE-2017-16920: v5/config/system.php in dayrui FineCms 5.2.0 has a default SYS_KEY value and does not require key regeneration

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2017-16920 is a critical-severity flaw (CVSS 9.8) affecting finecms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

v5/config/system.php in dayrui FineCms 5.2.0 has a default SYS_KEY value and does not require key regeneration for each installation, which allows remote attackers to upload arbitrary .php files via a member api swfupload action to index.php.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.1% (top 18%)
CISA exploited list	No
Published	2017-11-21
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: finecms

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

Am I affected?

Timeline

2017-11-21 13:29 UTCPublished CVE record published
2026-06-17 01:10 UTCUpdated Record last modified

finecms finecms DOWNGRADE

Affected: 5.2.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.2.0 (Debian / Ubuntu)

apt-cache madison finecms sudo apt install finecms=<VERSION_BEFORE_5.2.0> sudo apt-mark hold finecms

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

dnf --showduplicates list finecms sudo dnf downgrade finecms-<VERSION_BEFORE_5.2.0> sudo dnf versionlock add finecms

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-2017-16920?

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

Is CVE-2017-16920 being exploited?

CVE-2017-16920 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-2017-16920 affect?

CVE-2017-16920 affects finecms. Severity is critical (CVSS 9.8). v5/config/system.php in dayrui FineCms 5.2.0 has a default SYS_KEY value and does not require key regeneration for each installation, which allows remote attackers to upload arbitrary .php files via a member api swfupload action to index.ph

How urgent is CVE-2017-16920?

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

Software pages

PHP vulnerabilities

Related CVEs

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CVE-2018-6893 CRITICAL 9.8 DOWNGRADE controllers/member/Api.php in dayrui FineCms 5.2.0 has SQL Injection: a request with s=member,c=api,m=checktit
CVE-2018-18191 HIGH 8.8 DOWNGRADE Cross-site request forgery (CSRF) vulnerability in /admin.php?c=member&m=edit&uid=1 in dayrui FineCms 5.4 allo
CVE-2017-9252 MEDIUM 6.1 MITIGATE andrzuk/FineCMS through 2017-05-28 is vulnerable to a reflected XSS in the search page via the text-search par
CVE-2017-9251 MEDIUM 6.1 MITIGATE andrzuk/FineCMS through 2017-05-28 is vulnerable to a reflected XSS in the sitename parameter to admin.php.

References

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