FastNetMon Community Edition up to 1.2.9 BGP NLRI Decoder src/bgp_protocol.cpp decode_bgp_subnet_encoding_ipv4_raw stack-based overflow

Summaryinfo

A vulnerability has been found in FastNetMon Community Edition up to 1.2.9 and classified as critical. The impacted element is the function decode_bgp_subnet_encoding_ipv4_raw of the file src/bgp_protocol.cpp of the component BGP NLRI Decoder. The manipulation leads to stack-based overflow. This vulnerability is traded as CVE-2026-48686. There is no exploit available.

Detailsinfo

A vulnerability was found in FastNetMon Community Edition up to 1.2.9. It has been rated as critical. This issue affects the function decode_bgp_subnet_encoding_ipv4_raw of the file src/bgp_protocol.cpp of the component BGP NLRI Decoder. 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:

FastNetMon Community Edition through 1.2.9 contains a stack-based buffer overflow in the BGP NLRI (Network Layer Reachability Information) decoder. The function decode_bgp_subnet_encoding_ipv4_raw() in src/bgp_protocol.cpp reads prefix_bit_length directly from the BGP packet (line 99) without validating it is 32 causes undefined behavior.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-48686 since 05/22/2026. The exploitation is known to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/19/2026).

The vulnerability scanner Nessus provides a plugin with the ID 321184 (Ubuntu 20.04 LTS / 24.04 LTS / 26.04 LTS : FastNetMon vulnerabilities (USN-8429-1)), 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 vulnerability database at Tenable (321184). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• FastNetMon

Name

• Community Edition

Version

• 1.2.0
• 1.2.1
• 1.2.2
• 1.2.3
• 1.2.4
• 1.2.5
• 1.2.6
• 1.2.7
• 1.2.8
• 1.2.9

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CPE 2.2info

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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