CVE-2026-89147
HighCVSS 7.5Summary
Net-SNMP through 5.9.5.2 contains a denial of service vulnerability in the SMUX module where smux_accept() performs an unauthenticated blocking read without timeout on newly accepted connections. An unauthenticated remote client can connect to the SMUX listener and send no data, causing the single-threaded snmpd main loop to block indefinitely and suspend all SNMP processing.
Risk Assessment
An attacker can remotely paralyze the SNMP service, preventing monitoring and management of network devices. This leads to serious disruption of infrastructure oversight.
Recommendation
Update Net-SNMP to a version containing the fix. Until then, restrict access to the SMUX port via firewall or disable the SMUX module if not used.
Other vulnerabilities in Net-SNMP
See all- CVE-2015-5621High
The snmp_pdu_parse function in net-snmp version 5.7.2 and earlier does not remove the varBind variable in a netsnmp_variable_list item when parsing of the SNMP PDU fails. This allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted packet.
- CVE-2008-4309High
Heap buffer overflow in the netsnmp_create_subtree_cache function in net-snmp before version 5.4.2.1, 5.3.2.3, and 5.2.5.1 allows remote attackers to cause a denial of service (crash) via a crafted SNMP GETBULK request.
Original NVD description (English source)
Net-SNMP through 5.9.5.2 contains a denial of service vulnerability in the SMUX module where smux_accept() performs an unauthenticated blocking read without timeout on newly accepted connections. An unauthenticated remote client can connect to the SMUX listener and send no data, causing the single-threaded snmpd main loop to block indefinitely and suspend all SNMP processing.