Security readout for executives and security teams
Plain-English summary
CVE-2026-24858 is a critical Fortinet authentication bypass affecting multiple Fortinet security products when FortiCloud SSO is enabled. A person with a FortiCloud account and registered device may be able to access devices registered to other accounts. Because CISA lists it as known exploited, affected environments should treat this as urgent.
Executive priority
Treat this as an emergency Fortinet remediation item. It affects security infrastructure, has a critical score, and is KEV-listed. Prioritize assets with FortiCloud SSO enabled and management interfaces reachable from untrusted networks.
Technical view
The issue is CWE-288, authentication bypass using an alternate path or channel. Affected ranges include FortiOS, FortiManager, FortiAnalyzer, FortiProxy, FortiWeb, and FortiNAC-F. The CVSS 3.1 score is 9.4 with network access, low complexity, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is highest where affected Fortinet versions use FortiCloud SSO. The bundle does not prove exposure for devices without FortiCloud SSO enabled. Internet-facing administration or broadly reachable management planes would increase business risk.
Exploitation context
Active exploitation is supported by the CISA KEV reference in the source bundle. Fortinet also published analysis of SSO abuse on FortiOS. The bundle does not include exploit mechanics, affected tenant counts, or confirmed exploitation against every listed product.
Researcher notes
The key exposure condition is FortiCloud SSO enabled on affected versions. The source bundle supports broad product impact and active exploitation, but does not provide safe validation probes, exploit details, or complete fixed-version mapping in the supplied text.
Mitigation direction
- Identify affected Fortinet products and versions across the environment.
- Confirm whether FortiCloud SSO is enabled on each device.
- Apply Fortinet PSIRT fixed releases or vendor-approved workarounds for FG-IR-26-060.
- If upgrade is delayed, assess disabling FortiCloud SSO using vendor guidance.
- Restrict administrative access paths and review FortiCloud SSO authentication monitoring.
Validation and detection
- Compare deployed versions against the affected ranges in CVE-2026-24858.
- Verify FortiCloud SSO configuration per device and account.
- Check CISA KEV status for required remediation handling.
- Review authentication logs for unexpected FortiCloud SSO access.
- Confirm remediation against Fortinet PSIRT FG-IR-26-060.
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-288: 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 lookupCVE-2026-24858 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
- 9.4 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/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.
CISA KEV status
SSVC decision data
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:O/RC:C3.95.9fortinetVulnerability scoring details
Base CVSS 3.1 score
9.4CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://fortiguard.fortinet.com/psirt/FG-IR-26-060CVE reference, fortinet
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24858CVE reference, CISA-ADP · government-resource
- https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortiosCVE reference, CISA-ADP · vendor-advisory
- https://cert-portal.siemens.com/productcert/html/ssa-975644.htmlCVE reference, siemens-SADP
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 Using an Alternate Path or Channel
Authentication Bypass Using an Alternate Path or Channel represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.