Security readout for executives and security teams
Plain-English summary
CVE-2020-21055 describes a directory traversal flaw in FusionPBX 4.5.7 that could let a malicious user rename files outside the intended area. In business terms, this could disrupt PBX operations or damage application/system files, depending on permissions. The sources do not provide a CVSS score or confirmed exploitation.
Executive priority
Treat this as a high-priority maintenance and exposure-reduction issue for FusionPBX 4.5.7. Urgency is higher for internet-facing or broadly accessible PBX administration portals. Evidence is incomplete, so prioritize verification before emergency response language.
Technical view
The CVE description says app\edit\filerename.php accepts folder, filename, and newfilename variables in a way that allows directory traversal and arbitrary file rename. The bundle identifies FusionPBX 4.5.7. Authentication requirements, affected configurations, CVSS, and CWE details are not provided in the source bundle.
Likely exposure
Likely exposure is limited to FusionPBX 4.5.7 deployments where the vulnerable file rename functionality is reachable by a malicious user. Internet-exposed management interfaces raise concern, but the sources do not confirm unauthenticated access or affected versions beyond 4.5.7.
Exploitation context
CISA KEV status is false in the provided bundle. Public references include a disclosure blog and a FusionPBX commit, but the supplied evidence does not confirm active exploitation, exploit maturity, or real-world attacks.
Researcher notes
Key unknowns are authentication requirements, exact privilege needed, affected version range, and security impact after arbitrary rename. The commit is relevant for patch analysis, but the bundle does not include enough detail to assert root cause beyond traversal in rename parameters.
Mitigation direction
- Inventory FusionPBX deployments and confirm whether version 4.5.7 is present.
- Review FusionPBX vendor guidance and commit 1a88ca61a744914d3336cc15a40fb3edbcde9085.
- Upgrade or apply the vendor-supported fix where applicable.
- Restrict FusionPBX administration access to trusted networks or VPN users.
- Run the web service with least-privilege filesystem permissions.
- Ensure recent backups exist for PBX configuration and related system files.
Validation and detection
- Check deployed FusionPBX version against the CVE description.
- Verify whether app\edit\filerename.php exists and is reachable.
- Confirm the vendor fix or equivalent patched code is present.
- Review web and system logs for unusual file rename activity.
- Validate file permissions limit the web process from modifying sensitive 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.
File 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-2020-21055 mapping review
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Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://resp3ctblog.wordpress.com/2019/10/28/fusionpbx-path-traversal-6/CVE reference · x_refsource_MISC
- https://github.com/fusionpbx/fusionpbx/commit/1a88ca61a744914d3336cc15a40fb3edbcde9085CVE reference · x_refsource_MISC
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.