CVE-2025-25249: Fortinet Multiple Products Heap-based Buffer Overflow Vulnerability

In short

Fortinet Multiple Products has a weakness classified as heap-based buffer overflow (CWE-122). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-09. NVD lists CVSS 3.1 at 9.8 CRITICAL.

What it is

“Fortinet FortiOS, FortiSwitchManager, and FortiSASE contain a heap-based buffer overflow vulnerability that allows an attacker to execute unauthorized code or commands via specially crafted packets.” — CISA KEV, retrieved 2026-11-01

“A heap-based buffer overflow vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11, FortiOS 7.0.0 through 7.0.17, FortiOS 6.4 all versions, FortiSwitchManager 7.2.0 through 7.2.6, FortiSwitchManager 7.0.0 through 7.0.5 allows attacker to execute unauthorized code or commands via specially crafted packets” — NVD, retrieved 2026-11-01

Who is affected

Fortinet Multiple Products. NVD lists the following versions as affected:

• Fortinet Fortios: from 6.4.0 inclusive, before 7.0.18
• Fortinet Fortios: from 7.2.0 inclusive, before 7.2.12
• Fortinet Fortios: from 7.4.0 inclusive, before 7.4.9
• Fortinet Fortios: from 7.6.0 inclusive, before 7.6.4
• Fortinet Fortiswitchmanager: from 7.0.0 inclusive, before 7.0.6
• Fortinet Fortiswitchmanager: from 7.2.0 inclusive, before 7.2.7
• Fortinet Fortisase: version 25.1.39
• Fortinet Fortisase: version 25.1.51
• Siemens Ruggedcom ape1808 Firmware: all versions listed (no range given)

Exploitation status

CISA KEV added: 2026-09-09. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-09-12.

Scores

NVD CVSS 3.1: 9.8 CRITICAL; vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source [email protected].

EPSS by FIRST: 3.74%; percentile 89.86; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-122, CWE-787.

Timeline

CISA required action

“Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.” — CISA KEV

What to do

• Confirm whether you run Fortinet Multiple Products and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Mitigation, Vendor Advisory: https://fortiguard.fortinet.com/psirt/FG-IR-25-084
• Third Party Advisory: https://cert-portal.siemens.com/productcert/html/ssa-864900.html
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.