Vulnerability Description
FastNetMon Community Edition through 1.2.9 is vulnerable to a local symlink attack via predictable file paths in /tmp. The statistics file path defaults to '/tmp/fastnetmon.dat' (src/fastnetmon.cpp line 159). The print_screen_contents_into_file() function (src/fastnetmon_logic.cpp line 2186) opens this path with std::ios::trunc without checking for symlinks or using O_NOFOLLOW. Additionally, the chmod() call on line 2190 always operates on cli_stats_file_path regardless of which file_path parameter was passed (a bug that applies wrong permissions), and the umask is set to 0 during daemonization (src/fastnetmon.cpp line 1821), making all created files world-writable. A local attacker can exploit this to overwrite arbitrary files as the FastNetMon process user (typically root).
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Pavel-Odintsov | Fastnetmon | <= 1.2.9 |
Related Weaknesses (CWE)
References
- https://github.com/pavel-odintsov/fastnetmonProduct
- https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon.cppProduct
- https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon_logic.cpProduct
- https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48693-symlink-tmpThird Party Advisory
FAQ
What is CVE-2026-48693?
CVE-2026-48693 is a vulnerability with a CVSS score of 5.5 (MEDIUM). FastNetMon Community Edition through 1.2.9 is vulnerable to a local symlink attack via predictable file paths in /tmp. The statistics file path defaults to '/tmp/fastnetmon.dat' (src/fastnetmon.cpp li...
How severe is CVE-2026-48693?
CVE-2026-48693 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-48693?
Check the references section above for vendor advisories and patch information. Affected products include: Pavel-Odintsov Fastnetmon.