Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability

Fortinet Multiple Products

Fortinet FortiOS, FortiSwitchMaster, FortiProxy, and FortiWeb contain an improper verification of cryptographic signature vulnerability that may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML message. Please be aware that CVE-2025-59719 pertains to the same problem and is mentioned in the same vendor advisory. Ensure to apply all patches mentioned in the advisory. Added to CISA KEV on 2025-12-16 (federal deadline 2025-12-23).

First seen: 16 Dec 2025
Last update: 16 Dec 2025, 12:00 UTC
Identifiers: CVE-2025-59718
Source: CISA KEV
On the menu as: VPN & firewalls

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Fortinet Multiple Products Improper Verification of Cryptographic Signature Vulnerability
Severity: high, exploited in the wild. Patch status: patched.
Affected: Fortinet Multiple Products
Ids: CVE-2025-59718

Fortinet FortiOS, FortiSwitchMaster, FortiProxy, and FortiWeb contain an improper verification of cryptographic signature vulnerability that may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML message. Please be aware that CVE-2025-59719 pertains to the same problem and is mentioned in the same vendor advisory. Ensure to apply all patches mentioned in the advisory. Added to CISA KEV on 2025-12-16 (federal deadline 2025-12-23).

## Steps
1. This touches infrastructure (vpn-edge). Look in terraform, ansible, cloud-init, Dockerfiles and docs for the product and version we run. If it isn't in the repo, say so and list what a human should check on the box.

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2025-59718") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://docs.fortinet.com/upgrade-tool/fortigate https://fortiguard.fortinet.com/psirt/FG-IR-25-647 https://nvd.nist.gov/vuln/detail/CVE-2025-59718
https://pwned.coffee/i/fortinet-multiple-products-improper-verification-of-cryp-cve-2025-59718

Sources

Totalone hot coffee