Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-24858 is a critical-severity Authentication Bypass Using an Alternate Path or Channel (CWE-288) vulnerability in Fortinet Fortianalyzer. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 0.3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-24858 is an authentication bypass vulnerability (CWE-288) affecting multiple Fortinet products when FortiCloud SSO authentication is enabled. Impacted versions include FortiAnalyzer 7.0.0–7.0.15, 7.2.0–7.2.11, 7.4.0–7.4.9 and 7.6.0–7.6.5; FortiManager in the same ranges; FortiNAC-F 7.6.3–7.6.5; FortiOS 7.0.0–7.0.18, 7.2.0–7.2.12, 7.4.0–7.4.10 and 7.6.0–7.6.5; FortiProxy 7.0.0–7.0.22, 7.2.0–7.2.15, 7.4.0–7.4.12 and 7.6.0–7.6.4; and FortiWeb 7.4.0–7.4.11, 7.6.0–7.6.6 and 8.0.0–8.0.3. The flaw permits an attacker to authenticate to devices they do not own by leveraging an alternate path through FortiCloud SSO.
An attacker who possesses a valid FortiCloud account and at least one registered device can exploit the issue to obtain administrative access to other organizations’ devices that also have FortiCloud SSO enabled. Successful exploitation grants full control equivalent to a legitimate administrator, including the ability to read, modify or delete configuration and data on the affected appliances. The vulnerability carries a CVSS 3.1 score of 9.8.
Fortinet advisory FG-IR-26-060 and the associated analysis blog describe the root cause and recommend immediate upgrade to the fixed releases listed in the bulletin; organizations that cannot patch promptly are advised to disable FortiCloud SSO authentication. The issue also appears in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild.
EPSS for the CVE rose sharply from a low baseline to a peak of 0.1645 on 28 January 2026 before receding to the current value of 0.0480, indicating a clear post-disclosure increase in exploitation interest.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-4712
Vulnerability Data
An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] vulnerability in Fortinet FortiAnalyzer 7.6.0 through 7.6.5, FortiAnalyzer 7.4.0 through 7.4.9, FortiAnalyzer 7.2.0 through 7.2.11, FortiAnalyzer 7.0.0 through 7.0.15, FortiManager 7.6.0 through 7.6.5, FortiManager 7.4.0 through 7.4.9, FortiManager 7.2.0…
more
through 7.2.11, FortiManager 7.0.0 through 7.0.15, FortiNAC-F 7.6.3 through 7.6.5, FortiOS 7.6.0 through 7.6.5, FortiOS 7.4.0 through 7.4.10, FortiOS 7.2.0 through 7.2.12, FortiOS 7.0.0 through 7.0.18, FortiProxy 7.6.0 through 7.6.4, FortiProxy 7.4.0 through 7.4.12, FortiProxy 7.2.0 through 7.2.15, FortiProxy 7.0.0 through 7.0.22, FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may 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.
- CWE(s)
- KEV Date Added
- 27 January 2026
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 7 hardening rules · 3 OS baselines
V6.4.3V6.6.1V12.1.3
Mitigating Controls (NIST 800-53 r5) AI
Requires a tamperproof, always-invoked reference monitor that structurally blocks bypass via any alternate path.
Enforces authorization checks on every logical access path, eliminating unauthenticated alternate channels.
Mandates unique identification and authentication for all organizational users, covering the primary authentication requirement.
Controls all external and key internal interfaces, reducing the chance of unauthenticated alternate channels.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Requiring authentication on every channel and path directly eliminates alternate-path bypasses.
Enforcing authorizations and least privilege across all access vectors prevents unauthenticated alternate paths.
Protecting networks and environments from unauthorized logical access blocks bypass via undocumented channels.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect alternate-path bypasses but does not prevent them in production.
Secure authentication control directly mitigates bypass by requiring strong, consistent authentication on all paths.
Access control policy directly addresses alternate authentication paths by requiring all channels to enforce authentication.
Authentication information management ensures credentials and mechanisms are consistently applied across all access paths.
Access rights provisioning and review prevent bypass via unmonitored or alternate channels.
Privileged access rights control reduces risk of bypass through elevated or alternate paths.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248598 There must be no ".shosts" files on the OL 8 operating system. prevents CWE-288
- V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-288
Oracle Linux 9 (2 rules)
- V-271757 OL 9 file systems must not contain shosts.equiv files. prevents CWE-288
- V-271758 OL 9 file systems must not contain .shosts files. prevents CWE-288
RHEL 7 (3 rules)
- V-204440 Red Hat Enterprise Linux operating systems version 7.2 or newer using Unified Extensible Firmware Interface (UEFI) must require authentication upon booting into single-user and maintenance modes. prevents CWE-288
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-288
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. prevents CWE-288