CVE-2026-48695

Published May 26, 2026

Last updated 11 days ago

CVSS high 8.1

Overview

Description
FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability in the MikroTik router integration plugin. The _log() function in src/mikrotik_plugin/fastnetmon_mikrotik.php (lines 107-108) constructs shell commands by concatenating the $msg parameter directly into exec() calls: exec("echo `date` \"- {FASTNETMON] - " . $msg . " \" >> " . $FILE_LOG_TMP). This is identical in pattern to the Juniper plugin vulnerability. The $msg variable contains unsanitized attack data from command-line arguments. An attacker who can influence argv[] values can inject arbitrary shell commands. The fix is to replace exec() with file_put_contents() or use escapeshellarg().
Source
cve@mitre.org
NVD status
Analyzed
Products
fastnetmon

Risk scores

CVSS 3.1

Type
Primary
Base score
8.1
Impact score
5.2
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Severity
HIGH

Weaknesses

nvd@nist.gov
CWE-78
134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-78

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.•CVE-2026-48689
  2. FastNetMon Community Edition through 1.2.9 has a buffer overflow, a different vulnerability than CVE-2026-48686 and CVE-2026-48689.•CVE-2026-48696
  3. FastNetMon Community Edition through 1.2.9 contains a configuration injection vulnerability in the Juniper router integration plugin. In src/juniper_plugin/fastnetmon_juniper.php, the $IP_ATTACK variable (received from argv[1]) is directly interpolated into Juniper NETCONF set-configuration commands at lines 69 and 90 without any validation or sanitization. Line 69: $conn->load_set_configuration("set routing-options static route {$IP_ATTACK} community 65535:666 discard"). Line 90: $conn->load_set_configuration("delete routing-options static route {$IP_ATTACK}/32"). An attacker who can control the IP address string can inject additional Juniper CLI configuration commands by embedding newline characters followed by arbitrary set/delete commands. This could modify the router's routing table, firewall filters, user accounts, or any other configuration element accessible via NETCONF. The impact is full router compromise.•CVE-2026-48694
  4. FastNetMon Community Edition through 1.2.9 does not verify TLS certificates on outbound HTTPS connections. The execute_web_request_secure() function in src/fast_library.cpp creates a boost::asio::ssl::context with tls_client mode and calls set_default_verify_paths() to load CA certificates, but never calls set_verify_mode(boost::asio::ssl::verify_peer). Without this call, OpenSSL performs the TLS handshake without validating the server's certificate chain, making all HTTPS connections vulnerable to man-in-the-middle attacks. This function is used for telemetry reporting to community-stats.fastnetmon.com, which sends system information including CPU model, kernel version, traffic statistics, and software configuration. An attacker can intercept and modify this data or redirect it to a malicious server.•CVE-2026-48697
  5. 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).•CVE-2026-48693

References

Sources include official advisories and independent security research.