Vulnerability Details CVE-2026-48690
FastNetMon Community Edition through 1.2.9 contains an integer overflow vulnerability in the packet capture buffer allocation. In src/packet_storage.hpp, the allocate_buffer() function computes memory_size_in_bytes as 'buffer_size_in_packets * (max_captured_packet_size + sizeof(fastnetmon_pcap_pkthdr_t)) + sizeof(fastnetmon_pcap_file_header_t)' using unsigned int (32-bit) arithmetic. With max_captured_packet_size=1500 and sizeof(fastnetmon_pcap_pkthdr_t)=16, each packet requires approximately 1516 bytes. If buffer_size_in_packets exceeds approximately 2,832,542, the multiplication overflows, resulting in a much smaller allocation than expected. Subsequent write_packet() calls then write past the allocated buffer, causing heap corruption. The buffer_size_in_packets value is derived from the ban_details_records_count configuration parameter, which is parsed using atoi() with no overflow checking.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 2.1%
CVSS Severity
CVSS v3 Score 7.1
References
Products affected by CVE-2026-48690
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.0.0
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.0
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.1
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.2
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.3
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.4
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.5
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.6
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.7
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.8
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.1.9
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.0
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.1
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.2
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.3
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.4
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.5
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.6
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.7
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cpe:2.3:a:pavel-odintsov:fastnetmon:1.2.8