CVE-2026-48689
FastNetMon Heap-Based Buffer Overflow Vulnerability
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.
INFO
Published Date :
May 26, 2026, 7:16 p.m.
Last Modified :
July 24, 2026, 11:10 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 3.1 | CRITICAL | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update FastNetMon Community Edition to a version beyond 1.2.9.
- Correct bounds checks in append_dynamic_buffer and related methods.
- Ensure all heap operations use proper length validation.
- Review usage of dynamic_binary_buffer_t for security.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-48689.
| URL | Resource |
|---|---|
| https://github.com/pavel-odintsov/fastnetmon | Product |
| https://github.com/pavel-odintsov/fastnetmon/blob/master/src/dynamic_binary_buffer.hpp | Product |
| https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48689-dynamic-buffer-off-by-one | Exploit Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-48689 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-48689
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-48689 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-48689 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: FastNetMon Community Edition, Description: FastNetMon Community Edition hasta la versión 1.2.9 contiene un desbordamiento de búfer basado en montículo por un byte en la clase dynamic_binary_buffer_t (src/dynamic_binary_buffer.hpp). Cinco métodos (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) utilizan una comprobación de límites incorrecta de la forma 'if (offset + length > maximum_internal_storage_size + 1)' en lugar de la correcta 'if (offset + length > maximum_internal_storage_size)'. Esto permite escribir exactamente un byte más allá del final del búfer asignado en el montículo. La clase se utiliza de forma generalizada en la codificación/decodificación de mensajes BGP, el procesamiento de plantillas NetFlow y la construcción de NLRI de Flow Spec. Un atacante que puede enviar tráfico de red (NetFlow, sFlow, IPFIX o BGP) a una instancia de FastNetMon puede desencadenar este desbordamiento, logrando potencialmente ejecución de código arbitrario al corromper los metadatos del montículo. Cabe destacar que el método append_byte() utiliza la comprobación de límites correcta, confirmando la inconsistencia. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'n/a', 'product': 'n/a', 'versions': [{'status': 'affected', 'version': 'n/a'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-48689', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-27T00:20:15.356833Z'} -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 27, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-122 Added CWE CWE-193 -
Initial Analysis by [email protected]
May. 26, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-787 Added CPE Configuration OR *cpe:2.3:a:pavel-odintsov:fastnetmon:*:*:*:*:community:*:*:* versions up to (including) 1.2.9 Added Reference Type MITRE: https://github.com/pavel-odintsov/fastnetmon Types: Product Added Reference Type MITRE: https://github.com/pavel-odintsov/fastnetmon/blob/master/src/dynamic_binary_buffer.hpp Types: Product Added Reference Type MITRE: https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48689-dynamic-buffer-off-by-one Types: Exploit, Third Party Advisory -
New CVE Received by [email protected]
May. 26, 2026
Action Type Old Value New Value Added 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. Added Reference https://github.com/pavel-odintsov/fastnetmon Added Reference https://github.com/pavel-odintsov/fastnetmon/blob/master/src/dynamic_binary_buffer.hpp Added Reference https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48689-dynamic-buffer-off-by-one