CVE-2026-89147
Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read
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.
- Record
CVE-2026-89147- CVSS 4.0
- 8.7 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-1088, CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2026-76036
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.
- Record
EUVD-2026-76036- CVSS 4.0
- 8.7 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-hv9m-8m5p-82j6
Net-SNMP through 5.9.5.2 contains a denial of service vulnerability in the SMUX module where...
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.
- Record
GHSA-hv9m-8m5p-82j6- CVSS 4.0
- 8.7 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-89147- CVSS 4.0
- 8.7 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400, CWE-1088
- Updated
- 2026-11-02
OSV
Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read
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.
- Record
CVE-2026-89147- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-1088, CWE-400
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-89147
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.
- Record
DEBIAN-CVE-2026-89147- CVSS 4.0
- 8.7 High
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 - Updated
- 2026-11-02
Show 4 moreShow less
OSVUBUNTU-CVE-2026-89147
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.
- Record
UBUNTU-CVE-2026-89147- CVSS 4.0
- 8.7 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-05
OSVAZL-101742 No score
CVE-2026-89147 affecting package net-snmp 5.9.5.2-1
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.
- Record
AZL-101742- Updated
- 2026-11-05
OSVROOT-OS-ALPINE-323-CVE-2026-89147 No score
CVE-2026-89147 in net-snmp - Patched by Root
Root has patched CVE-2026-89147 in the net-snmp package for Root:Alpine:3.23. Multiple fixed versions available.
- Record
ROOT-OS-ALPINE-323-CVE-2026-89147- Updated
- 2026-11-02
OSVUSN-8997-1 No score
net-snmp vulnerability
It was discovered that Net-SNMP incorrectly handled newly accepted connections in the SMUX module. An unauthenticated remote attacker could possibly use this issue to cause Net-SNMP to block indefinitely, resulting in a denial of service.
- Record
USN-8997-1- Updated
- 2026-11-05
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
net-snmpAzure Linux:3 |
through 5.9.5.2-1 | None known |
net-snmpDebian:12 |
All versions, plus listed versions 5.9.3+dfsg-25.9.3+dfsg-2+deb12u15.9.4+dfsg-15.9.4+dfsg-1.15.9.4+dfsg-1.1~exp1 Show 6 moreShow less5.9.4+dfsg-1.1~exp25.9.4+dfsg-25.9.5.2+dfsg-15.9.5.2+dfsg-25.9.5.2+dfsg-2.15.9.5.2+dfsg-3 |
None known |
net-snmpDebian:13 |
All versions, plus listed versions 5.9.4+dfsg-25.9.4+dfsg-2+deb13u15.9.5.2+dfsg-15.9.5.2+dfsg-25.9.5.2+dfsg-2.15.9.5.2+dfsg-3 |
None known |
net-snmpDebian:14 |
before 5.9.5.2+dfsg-3, plus listed versions 5.9.4+dfsg-25.9.5.2+dfsg-15.9.5.2+dfsg-25.9.5.2+dfsg-2.1 |
5.9.5.2+dfsg-3 |
net-snmpRoot:Alpine:3.23 |
before 5.9.5.2-r00071 | 5.9.5.2-r00071 |
rootio-net-snmpRoot:Alpine:3.23 |
before 5.9.5.2-r00071 | 5.9.5.2-r00071 |
net-snmpUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 5.7.2~dfsg-8ubuntu15.7.2~dfsg-8ubuntu25.7.2~dfsg-8.1ubuntu15.7.2~dfsg-8.1ubuntu25.7.2~dfsg-8.1ubuntu3 Show 7 moreShow less5.7.2~dfsg-8.1ubuntu3.15.7.2~dfsg-8.1ubuntu3.25.7.2~dfsg-8.1ubuntu3.35.7.2~dfsg-8.1ubuntu3.3+esm15.7.2~dfsg-8.1ubuntu3.3+esm25.7.2~dfsg-8.1ubuntu3.3+esm35.7.2~dfsg-8.1ubuntu3.3+esm4 |
None known |
net-snmpUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 5.7.3+dfsg-1ubuntu25.7.3+dfsg-1ubuntu35.7.3+dfsg-1ubuntu45.7.3+dfsg-1ubuntu4.15.7.3+dfsg-1ubuntu4.2 Show 6 moreShow less5.7.3+dfsg-1ubuntu4.35.7.3+dfsg-1ubuntu4.45.7.3+dfsg-1ubuntu4.55.7.3+dfsg-1ubuntu4.65.7.3+dfsg-1ubuntu4.6+esm15.7.3+dfsg-1ubuntu4.6+esm2 |
None known |
net-snmpUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 5.7.3+dfsg-1.7ubuntu15.7.3+dfsg-1.8ubuntu15.7.3+dfsg-1.8ubuntu25.7.3+dfsg-1.8ubuntu35.7.3+dfsg-1.8ubuntu3.1 Show 7 moreShow less5.7.3+dfsg-1.8ubuntu3.25.7.3+dfsg-1.8ubuntu3.35.7.3+dfsg-1.8ubuntu3.55.7.3+dfsg-1.8ubuntu3.65.7.3+dfsg-1.8ubuntu3.75.7.3+dfsg-1.8ubuntu3.85.7.3+dfsg-1.8ubuntu3.8+esm1 |
None known |
net-snmpUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 5.7.3+dfsg-5ubuntu55.7.3+dfsg-5ubuntu65.8+dfsg-2ubuntu15.8+dfsg-2ubuntu25.8+dfsg-2ubuntu2.1 Show 9 moreShow less5.8+dfsg-2ubuntu2.25.8+dfsg-2ubuntu2.35.8+dfsg-2ubuntu2.45.8+dfsg-2ubuntu2.55.8+dfsg-2ubuntu2.65.8+dfsg-2ubuntu2.75.8+dfsg-2ubuntu2.95.8+dfsg-2ubuntu2.9+esm15.8+dfsg-2ubuntu2.9+esm2 |
None known |
net-snmpUbuntu:22.04:LTS |
before 5.9.1+dfsg-1ubuntu2.10, plus listed versions 5.9+dfsg-3ubuntu25.9+dfsg-3ubuntu35.9+dfsg-3ubuntu45.9.1+dfsg-1ubuntu15.9.1+dfsg-1ubuntu2 Show 8 moreShow less5.9.1+dfsg-1ubuntu2.15.9.1+dfsg-1ubuntu2.25.9.1+dfsg-1ubuntu2.45.9.1+dfsg-1ubuntu2.55.9.1+dfsg-1ubuntu2.65.9.1+dfsg-1ubuntu2.75.9.1+dfsg-1ubuntu2.85.9.1+dfsg-1ubuntu2.9 |
5.9.1+dfsg-1ubuntu2.10 |
net-snmpUbuntu:24.04:LTS |
before 5.9.4+dfsg-1.1ubuntu3.3, plus listed versions 5.9.3+dfsg-2ubuntu35.9.4+dfsg-1ubuntu15.9.4+dfsg-1ubuntu25.9.4+dfsg-1.1ubuntu25.9.4+dfsg-1.1ubuntu35.9.4+dfsg-1.1ubuntu3.15.9.4+dfsg-1.1ubuntu3.2 |
5.9.4+dfsg-1.1ubuntu3.3 |
net-snmpUbuntu:26.04:LTS |
before 5.9.4+dfsg-2ubuntu3.1, plus listed versions 5.9.4+dfsg-2ubuntu25.9.4+dfsg-2ubuntu3 |
5.9.4+dfsg-2ubuntu3.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | OSV | |
| affected, facts | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-89147 is a high vulnerability (CVSS 8.7) in Net-snmp, published September 11, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.49%, the 42nd percentile. Fixed in net-snmp 5.9.5.2+dfsg-3.
References
gist.github.com/thesmartshadow/001cea595e75fed6aaea7389666dc9eb
github.com/net-snmp/net-snmp/blob/v5.9.5.2/agent/mibgroup/smux/smux.c
vulncheck.com/advisories/net-snmp-through-5.9.5.2-denial-of-service-via-blocking-unauthenticated-smux-read
nvd.nist.gov/vuln/detail/CVE-2026-89147