# CVE-2026-48683: fastnetmon: FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowse...

CVE-2026-48683 is fixed in fastnetmon on 1 platform, first by DEBIAN-CVE-2026-48683, released June 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-48683
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0033
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 26, 2026

## Description

FastNetMon Community Edition through 1.2.9 contains an out-of-bounds read vulnerability in the NetFlow v9 data flowset processor. In src/netflow_plugin/netflow_v9_collector.cpp, the Data template branch (lines 1695-1702) iterates over flow records without performing a per-iteration bounds check against the packet end pointer. In contrast, the Options template branch (lines 1709-1719) correctly checks 'if (pkt + offset + field_template->total_length > packet_end)' before each iteration. The Data branch omits this check entirely. Since template definitions are sent by the network peer (and are unauthenticated UDP), an attacker can craft templates that cause the parser to read arbitrary memory past the packet buffer. This can leak sensitive memory contents or cause a crash.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | fastnetmon Debian 13.5 (trixie) | 1.2.9-0+deb13u1 | [DEBIAN-CVE-2026-48683](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48683.md) | Jun 24, 2026 |
| Linux | fastnetmon Debian 14 | 1.2.9-1 | [DEBIAN-CVE-2026-48683](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48683.md) | Jun 24, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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