Fortinet FortiOS up to 5.6.12/6.0.10 SSL VPN stack-based overflow

Summaryinfo

A vulnerability, which was classified as critical, was found in Fortinet FortiOS up to 5.6.12/6.0.10. The affected element is an unknown function of the component SSL VPN. Executing a manipulation can lead to stack-based overflow. This vulnerability is handled as CVE-2020-12820. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Fortinet FortiOS up to 5.6.12/6.0.10 and classified as critical. This vulnerability affects some unknown functionality of the component SSL VPN. The manipulation with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is 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). As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.

The advisory is shared for download at fortiguard.fortinet.com. This vulnerability was named CVE-2020-12820 since 05/12/2020. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/22/2025).

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

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Firewall Software

Vendor

• Fortinet

Name

• FortiOS

Version

• 5.6.0
• 5.6.1
• 5.6.2
• 5.6.3
• 5.6.4
• 5.6.5
• 5.6.6
• 5.6.7
• 5.6.8
• 5.6.9
• 5.6.10
• 5.6.11
• 5.6.12
• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5
• 6.0.6
• 6.0.7
• 6.0.8
• 6.0.9
• 6.0.10

License

• commercial

Website

• Vendor: https://www.fortinet.com/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion