Security readout for executives and security teams
Plain-English summary
This FortiWAN flaw lets an unauthenticated remote attacker delete files through path traversal. The most business-relevant impact is that deleting certain configuration files can reset the Admin password to its default value, enabling loss of control over the appliance.
Executive priority
Treat as urgent for any affected FortiWAN deployment. The issue can enable unauthenticated disruption and potential administrative compromise, but the provided sources do not confirm active exploitation.
Technical view
CVE-2021-26102 is described as relative path traversal affecting FortiWAN 4.5.7 and below and all 4.4 versions. A crafted POST request can delete system files. Deleting specific configuration files can reset the Admin password to default. CVSS is 9.8 critical.
Likely exposure
Organizations running Fortinet FortiWAN 4.5.7 or earlier, or any 4.4 release, are the stated exposure set. Risk is highest where the vulnerable FortiWAN service is reachable by untrusted networks.
Exploitation context
The CVE record describes remote, unauthenticated exploitation with low complexity and no user interaction. The supplied sources do not show CISA KEV listing or confirmed active exploitation in the wild.
Researcher notes
The source bundle contains a mismatch: the description names CWE-23 path traversal, while the CWE list shows CWE-305. Rely on vendor advisory and CVE record for affected versions and remediation details.
Mitigation direction
- Check Fortinet PSIRT FG-IR-21-048 for vendor-supported remediation.
- Identify and upgrade or retire affected FortiWAN versions.
- Restrict access to FortiWAN interfaces from untrusted networks.
- Review Admin password state and reset credentials if exposure is suspected.
- Check appliance integrity and configuration before returning service to production.
Validation and detection
- Inventory FortiWAN appliances and record firmware versions.
- Confirm whether any device runs 4.5.7 or below, or 4.4.
- Verify remote reachability from untrusted networks.
- Review logs for unexpected file deletion or Admin password reset indicators.
- Validate current guidance against Fortinet PSIRT FG-IR-21-048.
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-305: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 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 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-2021-26102 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/E:H/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:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:U/RC:C3.95.9Primary 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/E:H/RL:U/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.fortinet.com/psirt/FG-IR-21-048CVE reference
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.
Authentication Bypass by Primary Weakness
Authentication Bypass by Primary Weakness represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.