How severe is CVE-2016-6909?

CVE-2016-6909 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-6909 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 50% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6909?

CVE-2016-6909 primarily affects Fortinet Fortios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6909?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2016-6909 published?

CVE-2016-6909 was published on 2016-08-24 and last updated on 2026-06-17.

CVE-2016-6909

CVE-2016-6909 is a critical-severity vulnerability in Fortinet Fortios with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 50% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-119.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 50% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Fortinet Fortios
Published: 2016-08-24
Last modified: 2026-06-17

Description

Buffer overflow in the Cookie parser in Fortinet FortiOS 4.x before 4.1.11, 4.2.x before 4.2.13, and 4.3.x before 4.3.9 and FortiSwitch before 3.4.3 allows remote attackers to execute arbitrary code via a crafted HTTP request, aka EGREGIOUSBLUNDER.

Frequently asked questions

What is CVE-2016-6909?: Buffer overflow in the Cookie parser in Fortinet FortiOS 4.x before 4.1.11, 4.2.x before 4.2.13, and 4.3.x before 4.3.9 and FortiSwitch before 3.4.3 allows remote attackers to execute arbitrary code via a crafted HTTP request, aka EGREGIOUSBLUNDER.
How severe is CVE-2016-6909?: CVE-2016-6909 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-6909 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 50% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6909?: CVE-2016-6909 primarily affects Fortinet Fortios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6909?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2016-6909 published?: CVE-2016-6909 was published on 2016-08-24 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortiswitch:*:*:*:*:*:*:*:*

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