Fortinet FortiOS up to 7.6.3 stack-based overflow

Summaryinfo

A vulnerability has been found in Fortinet FortiOS up to 6.4.16/7.0.18/7.2.12/7.4.8/7.6.3 and classified as critical. This impacts an unknown function. The manipulation leads to stack-based overflow. This vulnerability is referenced as CVE-2025-53843. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Fortinet FortiOS up to 6.4.16/7.0.18/7.2.12/7.4.8/7.6.3 and classified as critical. This issue affects an unknown part. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

A stack-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 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions allows attacker to execute unauthorized code or commands via specially crafted packets

The advisory is shared at fortiguard.fortinet.com. The identification of this vulnerability is CVE-2025-53843 since 07/10/2025. The exploitation is known to be difficult. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/21/2025).

The vulnerability scanner Nessus provides a plugin with the ID 275608 (Fortinet Fortigate Stack buffer overflow in CAPWAP daemon (FG-IR-25-358)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (275608) and CERT Bund (WID-SEC-2025-2624). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Fortinet FortiOS

Productinfo

Type

• Firewall Software

Vendor

• Fortinet

Name

• FortiOS

Version

• 6.4.0
• 6.4.1
• 6.4.2
• 6.4.3
• 6.4.4
• 6.4.5
• 6.4.6
• 6.4.7
• 6.4.8
• 6.4.9
• 6.4.10
• 6.4.11
• 6.4.12
• 6.4.13
• 6.4.14
• 6.4.15
• 6.4.16
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9
• 7.0.10
• 7.0.11
• 7.0.12
• 7.0.13
• 7.0.14
• 7.0.15
• 7.0.16
• 7.0.17
• 7.0.18
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9
• 7.2.10
• 7.2.11
• 7.2.12
• 7.4.0
• 7.4.1
• 7.4.2
• 7.4.3
• 7.4.4
• 7.4.5
• 7.4.6
• 7.4.7
• 7.4.8
• 7.6.0
• 7.6.1
• 7.6.2
• 7.6.3

License

• commercial

Website

• Vendor: https://www.fortinet.com/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

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Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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