CVE-2026-48685

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Summary

CVECVE-2026-48685
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-26 16:16:26 UTC
Updated2026-05-27 14:23:59 UTC
DescriptionFastNetMon 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

Problem Types: CWE-130 | n/a | CWE-130 CWE-130 Improper Handling of Length Parameter Inconsistency

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1ADPDECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Pavel-odintsov Fastnetmon All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp [email protected] github.com Product
github.com/pavel-odintsov/fastnetmon [email protected] github.com Product
lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length [email protected] lorikeetsecurity.com Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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