CVE-2026-48689 Memory corruption in n/a
An off-by-one heap buffer overflow in FastNetMon allows remote attackers to achieve arbitrary code execution via crafted network traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48689?
CVE-2026-48689 is a critical memory corruption vulnerability in n/a, published on 26 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-48689?
It affects 1 product.
Products include Pavel-Odintsov Fastnetmon.
How do I fix CVE-2026-48689?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-48689 being exploited?
There is no known exploitation of CVE-2026-48689 in the wild and no public exploit code.
Other vulnerabilities in n/a
Sources
Also known as DEBIAN-CVE-2026-48689, GHSA-5444-f65m-f3c8, UBUNTU-CVE-2026-48689.