Security readout for executives and security teams
Plain-English summary
FortiSandbox versions before 4.0.0 may generate RPC API session IDs from too small a random space. A low-privileged attacker with some device state information could possibly predict a valid session ID and access confidential information.
Executive priority
Treat as a planned security update unless the RPC API is exposed to untrusted users. Prioritize faster remediation for internet-adjacent or broadly reachable management networks.
Technical view
The issue is weak session ID unpredictability in the FortiSandbox RPC API. The CVSS 3.1 vector rates network access, high attack complexity, low privileges required, no user interaction, and high confidentiality impact only.
Likely exposure
Exposure is limited to Fortinet FortiSandbox deployments running versions before 4.0.0, particularly where the RPC API is reachable by low-privileged or less-trusted users.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation. The CVSS temporal field indicates proof-of-concept maturity, but the provided sources do not include exploit details.
Researcher notes
Key uncertainty is the required “few information pieces” about device state. Assess real-world risk by validating version, RPC API reachability, privilege boundaries, and session monitoring coverage.
Mitigation direction
- Upgrade FortiSandbox to version 4.0.0 or later following Fortinet guidance.
- Restrict RPC API access to trusted administrative networks only.
- Review Fortinet advisory FG-IR-20-218 for vendor-specific remediation details.
- Monitor FortiSandbox sessions and authentication activity for unusual access patterns.
Validation and detection
- Inventory FortiSandbox appliances and record installed versions.
- Confirm whether any deployment is running a version before 4.0.0.
- Verify RPC API exposure from user, management, and untrusted network segments.
- Review logs for suspicious session reuse or unexpected RPC API access.
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.
CVE-2021-26098 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
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/RL:X/RC:X
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:L/UI:N/S:U/C:H/I:N/A:N/E:P/RL:X/RC:X1.63.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/RL:X/RC:X
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.com/advisory/FG-IR-20-218CVE 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.