Security readout for executives and security teams
Plain-English summary
FortiWAN appliances before version 4.5.9 contain stack buffer overflow flaws that could let an unauthenticated network attacker run code on the device. This is serious because FortiWAN is infrastructure equipment, but the CVSS vector marks attack complexity as high and the bundle does not show known active exploitation.
Executive priority
Prioritize remediation for internet-reachable or business-critical FortiWAN deployments. Treat this as high urgency, but not emergency-level without evidence of exposure or active exploitation.
Technical view
CVE-2021-26112 covers multiple CWE-121 stack-based buffer overflows in FortiWAN network daemons and command line interpreter before 4.5.9. The CVSS 3.1 score is 8.1 with network access, no privileges, no user interaction, high impact to confidentiality, integrity, and availability, and proof-of-concept exploit maturity.
Likely exposure
Organizations using Fortinet FortiWAN versions earlier than 4.5.9 are exposed, especially where FortiWAN management or service interfaces are reachable from untrusted networks.
Exploitation context
The provided data does not show CISA KEV listing or active exploitation. The CVSS vector includes E:P, indicating proof-of-concept exploit maturity, but that is not evidence of exploitation in the wild.
Researcher notes
Key unknowns are the exact affected daemons, CLI exposure assumptions, and operational indicators. The public bundle supports arbitrary code execution risk but does not provide safe detection signatures or detailed exploit conditions.
Mitigation direction
- Upgrade FortiWAN appliances to version 4.5.9 or later.
- Review Fortinet advisory FG-IR-21-065 for vendor-specific remediation guidance.
- Restrict FortiWAN access to trusted administrative networks.
- Monitor FortiWAN services for crashes, restarts, or suspicious requests.
Validation and detection
- Inventory all FortiWAN appliances and record firmware versions.
- Confirm no appliance runs FortiWAN earlier than 4.5.9.
- Check whether FortiWAN interfaces are reachable from untrusted networks.
- Review FortiWAN logs for abnormal daemon failures or unexpected access attempts.
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.
Execution 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 lookupCVE-2021-26112 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:H/PR:N/UI:N/S:U/C:H/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:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:C2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.com/psirt/FG-IR-21-065CVE 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.