Security readout for executives and security teams
Plain-English summary
CVE-2021-44159 is a critical flaw in 4MOSAn GCB Doctor. An unauthenticated remote attacker can upload arbitrary files, including webshells, through the product’s upload function. The source says this can lead to arbitrary code execution, system operations, or denial of service.
Executive priority
Treat as urgent if GCB Doctor is deployed, because the published impact is unauthenticated remote code execution with full CIA impact. Prioritize asset discovery first, since affected versions and patch status are not specified in the provided sources.
Technical view
The vulnerability is CWE-434 unrestricted upload of dangerous file type with improper privilege control. CVSS 3.1 is 9.8: network exploitable, low complexity, no privileges, no user interaction, with high confidentiality, integrity, and availability impact. Affected versions are not specified in the provided sources.
Likely exposure
Exposure is limited to organizations running 4MOSAn GCB Doctor, especially if the file upload function is reachable from untrusted networks. The source bundle does not identify specific versions, deployment patterns, CPEs, or default exposure, so asset confirmation is required.
Exploitation context
The CVE description supports unauthenticated remote file upload leading to code execution or denial of service. The provided bundle does not show CISA KEV listing, public exploitation confirmation, exploit maturity, or observed attacks, so active exploitation should not be assumed from these sources.
Researcher notes
The public record is sparse. Key gaps are affected version range, fixed version, vendor workaround, and exploitation evidence. Analysis should stay scoped to 4MOSAn GCB Doctor and avoid extending impact to other 4MOSAn products without additional source support.
Mitigation direction
- Confirm whether 4MOSAn GCB Doctor is deployed anywhere in the environment.
- Check 4MOSAn or TWCERT guidance for any official patch or workaround.
- Remove internet exposure for GCB Doctor if business use does not require it.
- Restrict access to trusted networks until remediation is confirmed.
- Review upload handling and executable-file controls with the vendor.
Validation and detection
- Inventory systems for 4MOSAn GCB Doctor installations and exposed upload functionality.
- Confirm product version and support status with the vendor or maintainer.
- Review web server and application logs for unexpected uploaded files.
- Check affected hosts for suspicious new files or process activity.
- Validate remediation through approved defensive testing, not exploit reproduction.
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-2021-44159 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
- https://www.twcert.org.tw/tw/cp-132-5395-eee40-1.htmlCVE 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.
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.