CVE-2026-89147
Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read
No known exploitation. EPSS puts it in the 39th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.5% chance of exploitation activity in the next 30 days, which ranks it in the 39th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
6 events over 13 days, from the signal feeds we watch.
- Record updated
- Record updated
- Publishedweakness classified, att&ck mapped, record updated
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Scored 7.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity NoneNo integrity impact
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb
- github.com/net-snmp/net-snmp
- github.com/net-snmp/net-snmp/blob/v5.9.5.2/agent/mibgroup/smux/smux.c
And 1 more reference. See all after sign-in
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