# CVE-2026-48696: FastNetMon Community Edition buffer overflow in ExaBGP action handler

Source: https://junglewise.ai/threats/cve-2026-48696-fastnetmon-community-edition-buffer-overflow-in-exabgp-action  
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-2026-48696 · Severity: info · CVSS 6 · Published 2026-05-26

FastNetMon Community Edition, a tool used by network administrators to detect and mitigate DDoS attacks, contains a security flaw in how it handles BGP routing commands. An attacker with the ability to modify the software's configuration file can insert a specially crafted string that causes the program to crash or potentially execute unauthorized code when a DDoS attack is detected. This could allow an attacker to gain full control over the monitoring server or disable network protection during a critical event.

## Quick answers

**Is CVE-2026-48696 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48696 being exploited in the wild.

**How severe is CVE-2026-48696?** Informational severity, with a CVSS score of 6, published 26 May 2026.

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

**Is there a fix for CVE-2026-48696?** 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-2026-48696 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-48696?** 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 stack-based buffer overflow exists in 'src/actions/exabgp_action.cpp' within the 'exabgp_prefix_ban_manage()' function. The vulnerability is caused by the use of 'sprintf()' to format BGP commands into a fixed 256-byte stack buffer without bounds checking. While the prefix and next-hop variables are naturally bounded by IP address lengths, the 'exabgp_community' value is read directly from 'fastnetmon.conf' without length validation. An attacker with local access to the configuration file can provide a long community list (e.g., 30+ entries) to overflow the buffer by approximately 74+ bytes, overwriting the saved return address. Because the binary lacks modern protections like stack canaries (-fstack-protector) and PIE, this can lead to arbitrary code execution when the function returns during a DDoS mitigation event. As of May 2026, no official patch has been released.

## Affected products

- FastNetMon FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-04-25: other: Vendor notified by Lorikeet Security
- 2026-05-23: disclosed: Public disclosure by Lorikeet Security
- 2026-05-26: advisory: CVE-2026-48696 published by MITRE/NVD

## References

- [https://github.com/pavel-odintsov/fastnetmon](https://github.com/pavel-odintsov/fastnetmon)
- [https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48696-exabgp-sprintf-overflow](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48696-exabgp-sprintf-overflow)