Net-SNMP through 5.9.5.2 contains a denial of service vulnerability in the SMUX module where smux_accept() performs an
Affects net-snmpSource GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 5 Nov 2026, 00:01 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in– |
Ubuntu Pro 16.04 LTSnet-snmppkg:deb/ubuntu/net-snmp?arch=source&distro=esm-infra/xenialOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
Net-SNMP versions through 5.9.5.2 contain a denial of service vulnerability in the SMUX module. The function smux_accept() performs an unauthenticated blocking read without a timeout on new connections. An unauthenticated remote attacker 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.
References
- ubuntu.com/security/CVE-2026-89147 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89147 (opens in a new tab)
- gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb (opens in a new tab)
- github.com/net-snmp/net-snmp (opens in a new tab)
- github.com/net-snmp/net-snmp/blob/v5.9.5.2/agent/mibgroup/smux/smux.c (opens in a new tab)
- vulncheck.com/advisories/net-snmp-through-5.9.5.2-denial-of-service-via-blocking-unauthenticated-smux-read (opens in a new tab)