---
id: CVE-2026-89147
title: >-
  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
summary: >-
  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 conn…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-1088
vendor: net-snmp
product: Net-SNMP
affected:
  - Net-SNMP <= 5.9.5.2
published: '2026-09-11'
updated: '2026-09-15'
sourceUpdated: '2026-09-15T17:17:33.660'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89147'
references:
  - url: 'https://gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/net-snmp/net-snmp'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/net-snmp/net-snmp/blob/v5.9.5.2/agent/mibgroup/smux/smux.c
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/net-snmp-through-5.9.5.2-denial-of-service-via-blocking-unauthenticated-smux-read
    label: disclosure@vulncheck.com
  - url: 'https://gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00276
epssPercentile: 0.20266
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-15T16:06:21.094512Z'
ingestedAt: '2026-09-11T16:45:47.924Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.