CVE-2026-48689
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Mixed 4 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Affected | — |
| sid | Fixed | 1.2.9-1 |
| forky | Affected | — |
| bookworm | Affected | — |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| pavel-odintsov | fastnetmon | {"endIncluding":"1.2.9"} | |
References
CWEs
CWE-787 CWE-122 CWE-193
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.