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CVE-2024-55591

Fortinet FortiOS and FortiProxy Authentication Bypass

9.8 CRITICALActively exploited (CISA KEV)Used in ransomwareEPSS 94.1%
  1. Published14 Jan 2025
  2. Added to CISA KEV14 Jan 2025
  3. Remediation due21 Jan 2025
Actively exploited (CISA KEV)

Fortinet FortiOS and FortiProxy contain an authentication bypass vulnerability that may allow an unauthenticated, remote attacker to gain super-admin privileges via crafted requests to Node.js websocket module.

Added to KEV: 14 Jan 2025Federal remediation due: 21 Jan 2025Used in ransomware

Description

An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] affecting FortiOS version 7.0.0 through 7.0.16 and FortiProxy version 7.0.0 through 7.0.19 and 7.2.0 through 7.2.12 allows a remote attacker to gain super-admin privileges via crafted requests to Node.js websocket module.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Fortinet FortiProxy≥ 7.0.0 < 7.0.20 · ≥ 7.2.0 < 7.2.13
Fortinet FortiOS≥ 7.0.0 < 7.0.17

Remediation

Fixed in
Fortinet FortiProxy≥ 7.0.20
Fortinet FortiOS≥ 7.0.17

References

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Frequently asked

Is CVE-2024-55591 being actively exploited?

Yes. CVE-2024-55591 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 14 Jan 2025. It has been used in ransomware campaigns.

How severe is CVE-2024-55591?

CVE-2024-55591 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 94.1% probability of exploitation.

Which products are affected by CVE-2024-55591?

Affected products include Fortinet FortiProxy, Fortinet FortiOS.

How do I fix CVE-2024-55591?

Upgrade affected software to a fixed version, for example Fortinet FortiProxy 7.0.20, Fortinet FortiOS 7.0.17 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2024-55591 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.