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High severity · published Sep 11, 2026
CVE-2026-89147
Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read
7.5
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 42% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NE
Net-SNMP · net-snmp
through 5.9.5.2 · source: vendor
Affected product
NE
Net-SNMP
net-snmp
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89147
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89147
gist.github.com
https://gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb
github.com
https://github.com/net-snmp/net-snmp
github.com
https://github.com/net-snmp/net-snmp/blob/v5.9.5.2/agent/mibgroup/smux/smux.c
www.vulncheck.com
https://www.vulncheck.com/advisories/net-snmp-through-5.9.5.2-denial-of-service-via-blocking-unauthenticated-smux-read
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