# CVE-2026-48685: FastNetMon Community Edition out-of-bounds access in BGP parser

Source: https://junglewise.ai/threats/cve-2026-48685-fastnetmon-community-edition-out-of-bounds-access-in-bgp-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-26. Updated: 2026-05-26  
License: CC BY 4.0 with a link back

CVE-2026-48685 · Severity: info · CVSS 6.5 · Published 2026-05-26

FastNetMon Community Edition, a DDoS detection and mitigation tool, contains a flaw in how it processes network routing information (BGP). An attacker can send specially crafted routing updates that cause the software to misinterpret network data, potentially leading to service crashes or incorrect security decisions. This could allow an attacker to bypass DDoS protections or disrupt the monitoring of network traffic.

## Quick answers

**Is CVE-2026-48685 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48685 being exploited in the wild.

**How severe is CVE-2026-48685?** Informational severity, with a CVSS score of 6.5, published 26 May 2026.

**Which products and versions are affected?** FastNetMon FastNetMon Community Edition through 1.2.9.

**Is there a fix for CVE-2026-48685?** 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-2026-48685 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-48685?** 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

A vulnerability exists in the `parse_raw_bgp_attribute()` function within `src/bgp_protocol.hpp`. While the parser correctly identifies the 'Extended Length' bit (indicating a 2-byte length field per RFC 4271), it only reads a single byte to determine the attribute value length. This results in length truncation for any attribute exceeding 255 bytes. The remaining bytes are then misinterpreted as subsequent attributes, causing cascading parse failures, 'phantom' attributes, and potential out-of-bounds memory reads. The vulnerability is reachable via BGP updates forwarded from an external daemon like GoBGP. As of May 2026, no official patch has been released.

## Affected products

- FastNetMon FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-04-25: disclosed: Lorikeet Security notified FastNetMon LTD
- 2026-05-23: advisory: Lorikeet Security published detailed advisory
- 2026-05-26: disclosed: CVE-2026-48685 published to NVD

## References

- [https://github.com/pavel-odintsov/fastnetmon](https://github.com/pavel-odintsov/fastnetmon)
- [https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp](https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp)
- [https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length)