CVE-2026-48685_CVE-2026-48685

6.5 / 10

MEDIUM

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

Description

FastNetMon Community Edition through 1.2.9 has out-of-bounds memory access because it incorrectly parses BGP path attributes with the extended length flag set. In src/bgp_protocol.hpp, the parse_raw_bgp_attribute() function correctly identifies when extended_length_bit is set and sets length_of_length_field to 2, but then reads only a single byte for the attribute value length (attribute_value_length = value[2] at line 173). Per RFC 4271 Section 4.3, when the Extended Length bit is set, the Attribute Length field is two octets and the value should be read as a 16-bit big-endian integer from value[2] and value[3]. As a result, any attribute longer than 255 bytes has its length silently truncated to the low byte (e.g., 300 bytes = 0x012C is read as 0x2C = 44 bytes). The remaining 256 bytes are then misinterpreted as subsequent attributes, causing cascading parse failures and potential out-of-bounds memory access.

Basic Information

ID CVE-2026-48685

Source mitre

Published May 26, 2026 at 00:00

Modified May 26, 2026 at 20:56

Affected Product

Vendor n/a

Product n/a

Version n/a

Affected Versions n/a n/a n/a

CWE Classification

CWE-130

References

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    "published": "2026-05-26T00:00:00.000Z",
    "modified": "2026-05-26T20:56:12.251Z",
    "type": "cve",
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    "references": "https://github.com/pavel-odintsov/fastnetmon\nhttps://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp\nhttps://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length",
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