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Fencer Vulns
high 7.5

CVE-2026-89147 json

Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read

published 2026-09-11 58 d ago modified 2026-09-24 45 d ago also EUVD-2026-76036

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

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 connect to the SMUX listener and send no data, causing the single-threaded snmpd main loop to block indefinitely and suspend all SNMP processing.

Patch / fix

  • net-snmp Debian 14 5.9.5.2+dfsg-3

debian advisories DEBIAN-CVE-2026-89147

  • net-snmp Ubuntu 22.04 LTS 5.9.1+dfsg-1ubuntu2.10
  • net-snmp Ubuntu 24.04 LTS 5.9.4+dfsg-1.1ubuntu3.3
  • net-snmp Ubuntu 26.04 LTS 5.9.4+dfsg-2ubuntu3.1

ubuntu advisories UBUNTU-CVE-2026-89147

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-89147 updated cvss 7.5

net-snmp: Net-SNMP: Denial of Service via unauthenticated SMUX read

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
54 d ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gist.github.com https://gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • net-snmp Net-SNMP

Classification

Weakness
  • CWE-1088 Synchronous Access of Remote Resource without Timeout
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.