CVE-2026-48689: n/a
FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.
AI Analysis
Technical Summary
CVE-2026-48689 is an off-by-one heap-based buffer overflow vulnerability in FastNetMon Community Edition (up to version 1.2.9) within the dynamic_binary_buffer_t class. Five methods incorrectly check buffer bounds, allowing a single byte to be written beyond the allocated heap buffer size. This class is integral to processing BGP messages, NetFlow templates, and Flow Spec NLRI, meaning the vulnerability can be triggered by specially crafted network traffic (NetFlow, sFlow, IPFIX, or BGP). Exploitation could lead to heap metadata corruption and potential arbitrary code execution. The vulnerability arises from an incorrect conditional check that permits offset + length to exceed the maximum internal storage size by one byte.
Potential Impact
An attacker capable of sending crafted network traffic to a vulnerable FastNetMon instance can exploit this off-by-one heap overflow to corrupt heap metadata. This corruption may enable arbitrary code execution, posing a significant risk to the confidentiality, integrity, and availability of the affected system. No known exploits in the wild have been reported at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict or monitor network traffic sources that can send NetFlow, sFlow, IPFIX, or BGP data to FastNetMon instances to reduce exposure. Avoid exposing FastNetMon to untrusted networks. Follow vendor communications for updates on patches or official mitigations.
CVE-2026-48689: n/a
Description
FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-48689 is an off-by-one heap-based buffer overflow vulnerability in FastNetMon Community Edition (up to version 1.2.9) within the dynamic_binary_buffer_t class. Five methods incorrectly check buffer bounds, allowing a single byte to be written beyond the allocated heap buffer size. This class is integral to processing BGP messages, NetFlow templates, and Flow Spec NLRI, meaning the vulnerability can be triggered by specially crafted network traffic (NetFlow, sFlow, IPFIX, or BGP). Exploitation could lead to heap metadata corruption and potential arbitrary code execution. The vulnerability arises from an incorrect conditional check that permits offset + length to exceed the maximum internal storage size by one byte.
Potential Impact
An attacker capable of sending crafted network traffic to a vulnerable FastNetMon instance can exploit this off-by-one heap overflow to corrupt heap metadata. This corruption may enable arbitrary code execution, posing a significant risk to the confidentiality, integrity, and availability of the affected system. No known exploits in the wild have been reported at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict or monitor network traffic sources that can send NetFlow, sFlow, IPFIX, or BGP data to FastNetMon instances to reduce exposure. Avoid exposing FastNetMon to untrusted networks. Follow vendor communications for updates on patches or official mitigations.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mitre
- Date Reserved
- 2026-05-22T00:00:00.000Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a15ee6a891d628fdc6e7760
Added to database: 5/26/2026, 7:03:06 PM
Last enriched: 5/26/2026, 7:17:55 PM
Last updated: 5/26/2026, 9:50:12 PM
Views: 4
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