Security readout for executives and security teams
Plain-English summary
CVE-2021-47753 is a critical flaw in phpKF CMS 3.00 Beta y6. An unauthenticated internet user may upload a disguised script and run code on the server. For exposed sites, this can mean full website compromise, data theft, defacement, or server takeover.
Executive priority
Treat as urgent for any exposed phpKF CMS 3.00 environment. The vulnerability is remotely reachable, unauthenticated, and can lead to full system compromise. Prioritize containment, vendor guidance review, and replacement if no safe update path is available.
Technical view
The issue is an unrestricted file upload weakness, mapped to CWE-434. The CVE description states attackers can bypass file extension checks, upload a PHP file disguised as an image, rename it, and execute arbitrary commands through a web shell parameter. CVSS is 9.8: network-accessible, low complexity, no privileges, and no user interaction.
Likely exposure
Highest concern is any internet-facing phpKF CMS 3.00 or 3.00 Beta y6 deployment with upload functionality reachable by unauthenticated users. The provided sources do not identify other affected versions, CPEs, or hosted-service exposure.
Exploitation context
Exploit-DB lists a public exploit reference for this vulnerability. The source bundle does not show CISA KEV inclusion and provides no cited evidence of active exploitation in the wild. Treat public exploit availability as increasing urgency, but do not assume confirmed active exploitation.
Researcher notes
The strongest public indicators are the CVE record, CVSS 9.8 score, CWE-434 classification, and Exploit-DB reference. The bundle does not provide a vendor advisory, patch version, or evidence of active exploitation. Avoid extrapolating impact beyond phpKF CMS 3.00/Beta y6.
Mitigation direction
- Inventory all phpKF CMS deployments and confirm exact version.
- Remove public internet access to affected instances where possible.
- Disable unauthenticated upload functionality if business operations allow.
- Check the vendor site and download page for updated guidance or releases.
- If no supported fix exists, plan migration or replacement.
- Review web directories for unexpected executable uploads.
Validation and detection
- Confirm whether phpKF CMS 3.00 or Beta y6 is installed.
- Identify upload endpoints exposed to unauthenticated users.
- Check web server logs for suspicious upload and execution activity.
- Inspect upload directories for executable script files.
- Verify file upload controls block executable server-side content.
- Document compensating controls such as WAF rules or access restrictions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-434: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-47753 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- ExploitDB-50610CVE reference · exploit
- Official Vendor HomepageCVE reference · product
- Software Download PageCVE reference · product
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Unrestricted Upload of File with Dangerous Type
Unrestricted Upload of File with Dangerous Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.