Is CVE-2026-48689 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-48689 being exploited in the wild.

How severe is CVE-2026-48689?

Informational severity, with a CVSS score of 9.8, published 26 May 2026.

Which products and versions are affected?

FastNetMon FastNetMon Community Edition through 1.2.9.

Is there a fix for CVE-2026-48689?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-48689 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-48689?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-48689: FastNetMon Community Edition heap overflow in dynamic_binary_buffer_t

CVE-2026-48689 · Severity: info · CVSS 9.8 · Published 2026-05-26

FastNetMon is a high-performance DDoS sensor used to monitor network traffic and detect attacks. A vulnerability in its internal data handling allows a remote attacker to send specially crafted network traffic (such as BGP or NetFlow data) to crash the service or potentially take full control of the server. This could lead to a complete loss of network monitoring capabilities and unauthorized access to sensitive infrastructure.

Quick answers

Is CVE-2026-48689 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-48689 being exploited in the wild.
How severe is CVE-2026-48689?: Informational severity, with a CVSS score of 9.8, published 26 May 2026.
Which products and versions are affected?: FastNetMon FastNetMon Community Edition through 1.2.9.
Is there a fix for CVE-2026-48689?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-48689 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-48689?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An off-by-one heap-based buffer overflow exists in the dynamic_binary_buffer_t class within src/dynamic_binary_buffer.hpp. Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, and memcpy_from_object_ptr) utilize an incorrect bounds check of 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This flaw allows an attacker to write exactly one byte past the end of a heap-allocated buffer. The affected class is used extensively for BGP message encoding, NetFlow template processing, and Flow Spec NLRI construction. A remote, unauthenticated attacker can trigger this overflow by sending malicious NetFlow, sFlow, IPFIX, or BGP traffic, potentially leading to arbitrary code execution via heap metadata corruption (e.g., House of Einherjar or tcache-related techniques).

Affected products

FastNetMon FastNetMon Community Edition through 1.2.9

Timeline

2026-05-23: disclosed: Vulnerability details published by Lorikeet Security
2026-05-26: advisory: CVE-2026-48689 assigned and published to NVD

References

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