CVE-2019-15751: An unrestricted file upload vulnerability in SITOS six Build v6.2.1 allows remote attackers to execute arbitra

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2019-15751 is a critical-severity flaw (CVSS 9.8) affecting sitos six. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An unrestricted file upload vulnerability in SITOS six Build v6.2.1 allows remote attackers to execute arbitrary code by uploading a SCORM file with an executable extension. This allows an unauthenticated attacker to upload a malicious file (containing PHP code to execute operating system commands) to the web root of the application.

Why this priority

Critical severity
EPSS top 9%: very likely to be exploited
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	4.5% (top 9%)
CISA exploited list	No
Weakness	CWE-434
Published	2019-10-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: sitos

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

Am I affected?

Timeline

2019-10-07 12:15 UTCPublished CVE record published
2026-06-17 02:21 UTCUpdated Record last modified

sitos sitos six DOWNGRADE

Affected: 6.2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.2.1

1. Check installed version

apt-cache policy sitos-six || rpm -q sitos-six || sitos-six --version

2. No fixed release: DOWNGRADE to a release before 6.2.1 (Debian / Ubuntu)

apt-cache madison sitos-six sudo apt install sitos-six=<VERSION_BEFORE_6.2.1> sudo apt-mark hold sitos-six

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

dnf --showduplicates list sitos-six sudo dnf downgrade sitos-six-<VERSION_BEFORE_6.2.1> sudo dnf versionlock add sitos-six

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-2019-15751?

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

Is CVE-2019-15751 being exploited?

CVE-2019-15751 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-2019-15751 affect?

CVE-2019-15751 affects sitos six. Severity is critical (CVSS 9.8). An unrestricted file upload vulnerability in SITOS six Build v6.2.1 allows remote attackers to execute arbitrary code by uploading a SCORM file with an executable extension. This allows an unauthenticated attacker to upload a malicious file

How urgent is CVE-2019-15751?

Priority 62/100. Critical severity; EPSS top 9%: very likely to be exploited; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2019-15750 MEDIUM 6.1 DOWNGRADE A Cross-Site Scripting (XSS) vulnerability in the blog function in SITOS six Build v6.2.1 allows remote attack
CVE-2019-15749 MEDIUM 6.5 DOWNGRADE SITOS six Build v6.2.1 allows a user to change their password and recovery email address without requiring the
CVE-2019-15748 CRITICAL 9.8 DOWNGRADE SITOS six Build v6.2.1 permits unauthorised users to upload and import a SCORM 2004 package by browsing direct
CVE-2019-15747 HIGH 8.8 DOWNGRADE SITOS six Build v6.2.1 allows a user with the user role of Seminar Coordinator to escalate their permission to
CVE-2019-15746 CRITICAL 9.8 DOWNGRADE SITOS six Build v6.2.1 allows an attacker to inject arbitrary PHP commands

References

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