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CVE-2026-48691
CRITICAL · CVSS 9.8
EPSS exploitation probability: 0%
Published 2026-05-26T17:16:53.670 · Last modified 2026-06-17T10:55:11.290

Summary

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.

Affected products

pavel-odintsov — fastnetmon

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.