Security readout for executives and security teams
Plain-English summary
CVE-2021-47904 affects Phreesoft PhreeBooks 5.2.3. An authenticated user can abuse the Image Manager upload function to place executable PHP on the server, potentially taking over the application host. This is business-significant where PhreeBooks is internet-accessible or used by low-trust accounts.
Executive priority
Treat as high priority if PhreeBooks 5.2.3 is deployed, especially if internet-facing. Because exploitation can lead to full server compromise after authentication, prioritize inventory, access restriction, and vendor-guidance review. No active exploitation is confirmed in the provided sources.
Technical view
The issue is CWE-434: unrestricted upload of dangerous file types. Sources describe authenticated remote code execution through the Image Manager in PhreeBooks 5.2.3. CVSS 3.1 is 8.8, with network access, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely limited to organizations running PhreeBooks 5.2.3, especially instances reachable over the network by authenticated non-admin or low-trust users. The provided sources do not identify other affected versions.
Exploitation context
Public exploit references exist in ExploitDB, but the source bundle does not show CISA KEV listing or confirmed active exploitation. Exploitation requires valid application credentials, then abuse of upload handling to achieve server-side code execution.
Researcher notes
Evidence is source-limited. The record names PhreeBooks 5.2.3 only, describes authenticated RCE via Image Manager upload, and references public exploit materials. No official patch version or vendor advisory details are provided in the bundle, so remediation should be validated against current vendor guidance.
Mitigation direction
- Identify any PhreeBooks 5.2.3 deployments.
- Check Phreesoft or trusted advisory sources for vendor guidance or updates.
- Restrict PhreeBooks access to trusted networks or VPN users.
- Limit upload permissions to trusted administrative users where possible.
- Review web server controls preventing uploaded PHP execution.
- Back up and isolate suspicious exposed instances before investigation.
Validation and detection
- Confirm the installed PhreeBooks version is 5.2.3.
- Inventory internet-facing or broadly accessible PhreeBooks instances.
- Review Image Manager upload permissions and eligible user roles.
- Inspect upload directories for unexpected executable PHP files.
- Review web logs for suspicious upload and file-access patterns.
- Verify compensating controls block execution from upload paths.
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-2021-47904 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-49524CVE reference · exploit
- Official Vendor HomepageCVE reference · product
- ExploitDB-46645CVE reference · exploit
- Web Shell Payload GistCVE reference · product
- VulnCheck Advisory: PhreeBooks 5.2.3 - Remote Code ExecutionCVE 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.
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.