Vulnerability · Published May 26, 2026 · Assigned by mitre
CVE-2026-48692
High 8.1
In plain English
A high-severity missing authentication in the fastnetmon package (Debian). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).
Official description
FastNetMon Community Edition through 1.2.9 exposes a gRPC API server on port 50052 with no authentication mechanism. The server is initialized with grpc::InsecureServerCredentials() (src/fastnetmon.cpp line 477) and a source code comment explicitly acknowledges 'Listen on the given address without any authentication mechanism.' None of the RPC methods in src/api.cpp (ExecuteBan, ExecuteUnBan, GetBanlist, GetTotalTrafficCounters, etc.) perform any credential verification. The ExecuteBan and ExecuteUnBan methods trigger security-critical actions: BGP route announcements that can blackhole network traffic, and execution of external notification scripts via popen(). An attacker with local network access can ban arbitrary IP addresses (causing denial of service to legitimate traffic), unban active attacks (disabling DDoS mitigation), and trigger script execution. There is also no role-based access control separating read-only monitoring from destructive administrative operations.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | fastnetmon | no fix listed | DEBIAN-CVE-2026-48692 |
| Debian:13 | fastnetmon | no fix listed | DEBIAN-CVE-2026-48692 |
| Debian:14 | fastnetmon | no fix listed | DEBIAN-CVE-2026-48692 |
| Ubuntu:25.10 | fastnetmon | no fix listed | UBUNTU-CVE-2026-48692 |
| Ubuntu:26.10 | fastnetmon | no fix listed | UBUNTU-CVE-2026-48692 |
Affected products (as reported)
Weakness: CWE-306 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N