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CVE-2026-48686 Detail

Description

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 for IPv4 prefixes. This value is passed to how_much_bytes_we_need_for_storing_certain_subnet_mask() which computes ceil(prefix_bit_length / 8), returning up to 32 bytes for a prefix_bit_length of 255. The result is used as the length argument to memcpy() (line 106), which copies into a 4-byte uint32_t stack variable (prefix_ipv4). This causes a stack buffer overflow of up to 28 bytes, which can be exploited for arbitrary code execution. Additionally, the unvalidated prefix_bit_length is passed to convert_cidr_to_binary_netmask_local_function_copy() (line 111), where a shift of (32 - cidr) with cidr > 32 causes undefined behavior.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
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URL Source(s) Tag(s)
MITRE
MITRE
MITRE

Weakness Enumeration

CWE-ID CWE Name Source

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-48686
NVD Published Date:
05/26/2026
NVD Last Modified:
05/26/2026
Source:
MITRE