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CVE-2026-48682

MEDIUMCVSS 5.9/10EPSS 0.27%

Last modified

CVE-2026-48682 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read in the IPv4 packet parser. In src/simple_packet_parser_ng.cpp, after validating that the packet contains at least sizeof(ipv4_header_t) bytes (20 bytes), the code advances the local_pointer by '4 * ipv4_header->get_ihl()' (line 164) without validating that (a) IHL >= 5 (the minimum valid value per RFC 791), or (b) 4 * IHL bytes are actually available in the packet. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

Description

FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read in the IPv4 packet parser. In src/simple_packet_parser_ng.cpp, after validating that the packet contains at least sizeof(ipv4_header_t) bytes (20 bytes), the code advances the local_pointer by '4 * ipv4_header->get_ihl()' (line 164) without validating that (a) IHL >= 5 (the minimum valid value per RFC 791), or (b) 4 * IHL bytes are actually available in the packet. The IHL field is 4 bits, allowing values 0-15, so the advance can be 0-60 bytes. An IHL value of 15 with only 20 bytes validated causes a 40-byte over-read. An IHL of 0-4 causes the pointer to not advance past the IP header, resulting in the TCP/UDP header being parsed from IP header data (type confusion). This vulnerability is reachable via any packet capture interface.

Metrics

CVSS 3.1
5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability
0.27%

18.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-48682?
FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read in the IPv4 packet parser. In src/simple_packet_parser_ng.cpp, after validating that the packet contains at least sizeof(ipv4_header_t) bytes (20 bytes), the code advances the local_pointer by '4 * ipv4_header->get_ihl()' (line 164) without validating that (a) IHL >= 5 (the minimum valid value per RFC 791), or (b) 4 * IHL bytes are actually available in the packet. The IHL field is 4 bits, allowing values 0-15, so the advance can be 0-60 bytes. An IHL value of 15 with only 20 bytes validated causes a 40-byte over-read. An IHL of 0-4 causes the pointer to not advance past the IP header, resulting in the TCP/UDP header being parsed from IP header data (type confusion). This vulnerability is reachable via any packet capture interface.
How severe is CVE-2026-48682?
CVE-2026-48682 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.
How do I fix CVE-2026-48682?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST