# CVE-2026-48690: FastNetMon Community Edition heap overflow in packet capture buffer

Source: https://junglewise.ai/threats/cve-2026-48690-fastnetmon-community-edition-heap-overflow-in-packet-capture  
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-2026-48690 · Severity: info · CVSS 7 · Published 2026-05-26

FastNetMon Community Edition, a DDoS detection tool, contains a flaw in how it allocates memory for storing packet captures. If an administrator sets an excessively high value for the packet record count in the configuration file, the software miscalculates the required memory, leading to a much smaller allocation than needed. This results in a memory corruption (heap overflow) when the software attempts to write packet data, potentially allowing an attacker with configuration access to crash the service or execute malicious code.

Technologies: [FastNetMon LTD FastNetMon Community Edition](https://junglewise.ai/threats/technologies/fastnetmon-community-edition). Vendors: [FastNetMon LTD](https://junglewise.ai/threats/vendors/fastnetmon-ltd).

## Quick answers

**Is CVE-2026-48690 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48690 being exploited in the wild.

**How severe is CVE-2026-48690?** Informational severity, with a CVSS score of 7, published 26 May 2026.

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

**Is there a fix for CVE-2026-48690?** 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-2026-48690 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-48690?** Check whether you run FastNetMon LTD FastNetMon Community Edition at an affected version. 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

An integer overflow exists in `src/packet_storage.hpp` within the `allocate_buffer()` function. The software calculates `memory_size_in_bytes` using 32-bit unsigned integer arithmetic based on the `ban_details_records_count` configuration parameter. When this parameter exceeds approximately 2,832,542, the multiplication wraps around, resulting in an undersized heap allocation via `malloc()`. Subsequent calls to `write_packet()` perform `memcpy` operations into this undersized buffer without sufficient bounds checking, causing a heap-based buffer overflow. An attacker with the ability to modify the `fastnetmon.conf` file can exploit this to achieve arbitrary code execution or cause a denial-of-service. As of the advisory date, no official patch has been released.

## Affected products

- FastNetMon LTD FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-04-25: other: Vendor notified by Lorikeet Security
- 2026-05-23: advisory: Public disclosure by Lorikeet Security
- 2026-05-26: disclosed: CVE 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/packet_storage.hpp](https://github.com/pavel-odintsov/fastnetmon/blob/master/src/packet_storage.hpp)
- [https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48690-packet-storage-integer-overflow](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48690-packet-storage-integer-overflow)

## Related threats

- [FastNetMon Community Edition configuration injection in Juniper plugin](https://junglewise.ai/threats/cve-2026-48694-fastnetmon-community-edition-configuration-injection-in-juniper)
- [FastNetMon Community Edition improper TLS certificate validation in telemetry](https://junglewise.ai/threats/cve-2026-48697-fastnetmon-community-edition-improper-tls-certificate-validation)
- [FastNetMon Community Edition heap overflow in BGP AS_PATH encoder](https://junglewise.ai/threats/cve-2026-48691-fastnetmon-community-edition-heap-overflow-in-bgp-as-path-encoder)
- [FastNetMon Community Edition out-of-bounds read in NetFlow v9 parser](https://junglewise.ai/threats/cve-2026-48684-fastnetmon-community-edition-out-of-bounds-read-in-netflow-v9)
- [FastNetMon Community Edition out-of-bounds read in NetFlow v9 collector](https://junglewise.ai/threats/cve-2026-48683-fastnetmon-community-edition-out-of-bounds-read-in-netflow-v9)