# CVE-2026-48693: FastNetMon Community Edition symlink attack in /tmp statistics file

Source: https://junglewise.ai/threats/cve-2026-48693-fastnetmon-community-edition-symlink-attack-in-tmp-statistics  
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-2026-48693 · Severity: info · CVSS 7 · Published 2026-05-26

FastNetMon Community Edition, a DDoS detection tool, is vulnerable to a local security flaw that allows an attacker to overwrite critical system files. By exploiting predictable temporary file locations, a local user can trick the software into deleting or modifying files it has permission to access, typically with root privileges. This can lead to a complete system crash or unauthorized changes to system configurations.

## Quick answers

**Is CVE-2026-48693 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48693 being exploited in the wild.

**How severe is CVE-2026-48693?** Informational severity, with a CVSS score of 7, published 26 May 2026.

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

**Is there a fix for CVE-2026-48693?** 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-2026-48693 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-48693?** 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

FastNetMon Community Edition (up to v1.2.9) uses a predictable default statistics file path at /tmp/fastnetmon.dat. The function print_screen_contents_into_file() in src/fastnetmon_logic.cpp opens this path using std::ios::trunc without verifying if the path is a symbolic link or using the O_NOFOLLOW flag. Furthermore, the application sets a umask of 0 during daemonization, resulting in world-writable files, and contains a logic error in its chmod() calls. A local attacker can create a symlink at the predictable /tmp location pointing to a sensitive system file; when FastNetMon updates its statistics, it will truncate and overwrite the target file with the privileges of the FastNetMon process (often root).

## Affected products

- FastNetMon FastNetMon Community Edition through 1.2.9

## Timeline

- 2026-05-23: advisory: Lorikeet Security published detailed technical blog post
- 2026-05-26: disclosed: CVE-2026-48693 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/fastnetmon.cpp](https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon.cpp)
- [https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon_logic.cpp](https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon_logic.cpp)
- [https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48693-symlink-tmp](https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48693-symlink-tmp)