Security readout for executives and security teams
Plain-English summary
CMSimple 5.4 has a high-impact flaw where a logged-in user can abuse template editing to run PHP code on the server. This can lead to full compromise of the website and underlying hosting context. The source bundle does not show confirmed active exploitation, but it does include a public exploit reference.
Executive priority
Treat this as a high-priority website compromise risk for any CMSimple 5.4 deployment. Prioritize internet-facing systems and sites with multiple administrative users. If CMSimple is not used, document non-exposure and monitor for asset drift.
Technical view
CVE-2021-47735 is an authenticated remote code execution issue in CMSimple 5.4, mapped to CWE-94. The reported path is template editing: an authenticated attacker with a valid CSRF token can save malicious PHP into template files. CVSS 3.1 is 8.8 with network access, low complexity, and low privileges required.
Likely exposure
Exposure is likely limited to CMSimple 5.4 installations where attackers can obtain valid CMSimple credentials and access template editing. Internet-facing CMSimple administration increases risk. The provided sources do not identify other affected versions or platforms.
Exploitation context
A public ExploitDB entry is referenced, indicating exploit information is available. The bundle states KEV is false, and no cited source confirms active exploitation. The attack requires authentication and a valid CSRF token, but no user interaction beyond attacker access is indicated by the CVSS vector.
Researcher notes
The available sources support authenticated RCE in CMSimple 5.4 via template editing and public exploit availability. They do not provide a confirmed fixed version, official patch note, or active exploitation evidence. Avoid assuming broader version impact without vendor or advisory confirmation.
Mitigation direction
- Identify and prioritize any CMSimple 5.4 installations.
- Check CMSimple and advisory sources for vendor-provided fixes or upgrade guidance.
- Restrict CMSimple administrative access to trusted networks or VPN.
- Review and limit accounts allowed to edit templates.
- Remove or disable unused CMSimple administrative accounts.
Validation and detection
- Inventory CMSimple deployments and confirm version 5.4 status.
- Verify whether template editing is enabled and who can access it.
- Review web and CMS logs for unexpected template changes.
- Inspect template files for unauthorized PHP modifications.
- Confirm whether vendor guidance or an upgrade has been applied.
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-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process 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 lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-47735 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/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:L/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- ExploitDB-50356CVE reference · exploit
- Official CMSimple HomepageCVE reference · product
- VulnCheck Advisory: CMSimple 5.4 Authenticated Remote Code Execution via Template EditingCVE reference · third-party-advisory
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.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.