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CISA KEV · ACTIVELY EXPLOITED
HIGH severity

CVE-2025-25249 — Fortios

HIGH

CVE-2025-25249 is a high-severity (CVSS 8.1) CWE-122 vulnerability in fortinet fortios. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-09-09) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.

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…

Published
Updated
Affected
4 products
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

  • Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-09-09. Federal agencies were required to remediate by 2026-09-12.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2025-25249.

EPSS Exploitation Probability

via FIRST.org ↗
3.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs90th percentile — riskier than 90% of all scored CVEsHighest risk
0.00%1.67%3.34%5.01%0.0%3.9%Apr 26Jul 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2025-25249 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,189 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Description

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

Affected Products

4 products · 9 configurations
OS
fortiosfortinet
≥ 7.6.0 && < 7.6.4
range
Application
fortisasefortinet
2 versions
25.1.3925.1.51
Application
fortiswitchmanagerfortinet
≥ 7.2.0 && < 7.2.7
range
OS
ruggedcom ape1808 firmwaresiemens
all

Detection & mitigation playbook

Vendor / appliance

  1. Detect

    Inventory every fortinet fortios deployment and check each version against the affected-products list above.

  2. Fix

    Apply the fortinet fortios security patch or hotfix for CVE-2025-25249 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

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
O3 Security · Runtime Protection

Is CVE-2025-25249 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

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Actively Exploited: CVE-2025-25249: Fortios (High 8.1)