Vulnerability

CVE-2026-24858

Critical· 9.8KEVCVSS9.8EPSS4%

.rules3/5

Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability

Fortinet FortiAnalyzer, FortiManager, FortiOS, and FortiProxy contain an authentication bypass using an alternate path or channel that could allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.

Threat signal

100/100

Severe

Severity

critical

CVSS

9.8

EPSS

Active

KEV

CISA KEV — actively exploited

134d overdue

AffectedFortinet — Multiple Products

Added to KEV

2026-01-27

Federal patch due (BOD 22-01)

2026-01-30

Required action (CISA verbatim)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisory + references

CISA description: “Fortinet FortiAnalyzer, FortiManager, FortiOS, and FortiProxy contain an authentication bypass using an alternate path or channel that could allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.”

CVSS

v3.1via NVDOpen in FIRST calculator →

9.8/ 10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

3.95%

probability of exploitation in next 30 days

p89

higher than 89% of all CVEs

3-day trend↓ 0.8pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2026-24858. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: yes
impact: total
mission: support

Lifecycle

2026-01-27Added to CISA KEVransomware: Unknown
2026-01-27Published
2026-01-30Federal patch due (BOD 22-01)
2026-06-12Last modified2 sources

References

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.