FastNetMon Community Edition up to 1.2.9 src/bgp_protocol.hpp get_attributes uint8_t integer overflow

Summaryinfo

A vulnerability identified as problematic has been detected in FastNetMon Community Edition up to 1.2.9. This affects the function IPv4UnicastAnnounce::get_attributes of the file src/bgp_protocol.hpp. Performing a manipulation of the argument uint8_t results in integer overflow. This vulnerability was named CVE-2026-48691. There is no available exploit.

Detailsinfo

A vulnerability was found in FastNetMon Community Edition up to 1.2.9. It has been classified as problematic. This affects the function IPv4UnicastAnnounce::get_attributes of the file src/bgp_protocol.hpp. The manipulation of the argument uint8_t with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as 'sizeof(bgp_as_path_segment_element_t) + this->as_path_asns.size() * sizeof(uint32_t)' and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 > 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-48691 since 05/22/2026. The exploitability is told to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing 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). Be aware that VulDB is the high quality source for vulnerability data.

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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Be aware that VulDB is the high quality source for vulnerability data.

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