Security readout for executives and security teams
Plain-English summary
FortiWeb management interfaces on listed older versions have a path traversal flaw that can let a logged-in attacker delete arbitrary files or directories. This can disrupt service or damage device integrity, but the source bundle requires attacker authentication.
Executive priority
Treat as high priority for any FortiWeb appliance in the affected ranges. The main business risk is service disruption or device integrity damage from authenticated misuse. Prioritize upgrade planning and management-plane access control.
Technical view
CVE-2021-42753 is CWE-22 path traversal in the FortiWeb management interface. A network attacker with low privileges can trigger arbitrary file and directory deletion on the device filesystem. CVSS 3.1 is 8.1 high, with high integrity and availability impact and no confidentiality impact stated.
Likely exposure
Exposure is likely where FortiWeb management access exists on versions 6.4.1 and below, 6.3.15 and below, 6.2.x, 6.1.x, 6.0.x, 5.9.x, or 5.8.x. Risk increases if management access is broadly reachable or low-privileged accounts are weakly controlled.
Exploitation context
The bundle does not show CISA KEV listing or cited active exploitation. Exploitation is described as authenticated, network-accessible, low-complexity, and requiring no user interaction. Public exploit maturity is marked proof-of-concept in the CVSS vector, but no exploit details are provided here.
Researcher notes
The provided CVE data names FortiWeb and affected branches, but the structured affected field is not populated. Remediation specifics are not included in the bundle, so rely on Fortinet’s advisory for exact fixed releases and operational guidance.
Mitigation direction
- Check Fortinet advisory FG-IR-21-158 for fixed versions and vendor guidance.
- Upgrade affected FortiWeb appliances according to Fortinet’s advisory.
- Restrict FortiWeb management access to trusted administrative networks.
- Review and remove unnecessary low-privileged management accounts.
- Monitor appliance filesystem and administrative activity for unexpected deletion events.
Validation and detection
- Inventory FortiWeb appliances and record firmware versions.
- Confirm whether each appliance matches the affected version ranges.
- Verify management interfaces are not broadly reachable.
- Review management user accounts and recent administrative activity.
- Confirm remediation status against Fortinet advisory FG-IR-21-158.
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-2021-42753 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:P/RL:U/RC:C
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:N/I:H/A:H/E:P/RL:U/RC:C2.85.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:P/RL:U/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.com/psirt/FG-IR-21-158CVE reference · x_refsource_CONFIRM
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.