CVE-2026-48693
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).
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | affected | |
| debian | forky | affected | |
| debian | sid | affected | |
| debian | trixie | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| pavel-odintsov | fastnetmon | {"endIncluding":"1.2.9"} | |
References
- 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_logic.cpp
- https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48693-symlink-tmp
- https://security-tracker.debian.org/tracker/CVE-2026-48693
CWEs
CWE-59
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.