# CVE-2026-89147: Net-SNMP through 5.9.5.2 Denial of Service via Blocking Unauthenticated SMUX Read

> Unauthenticated remote attackers can cause a denial of service in Net-SNMP by blocking the SMUX listener, suspending all SNMP processing.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** AZL-101742, DEBIAN-CVE-2026-89147, ECHO-c070-0905-6b62, GHSA-hv9m-8m5p-82j6, ROOT-OS-ALPINE-323-CVE-2026-89147, UBUNTU-CVE-2026-89147

## What is CVE-2026-89147?

CVE-2026-89147 is a high-severity denial of service vulnerability in Net-SNMP, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-1088 (Synchronous Access of Remote Resource without Timeout)

## Which versions are affected by CVE-2026-89147?


## How do I fix CVE-2026-89147?

Upgrade to a fixed version.

## Is CVE-2026-89147 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-89147 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89147 and fix it if it is affected.

What it is: CVE-2026-89147 is a high-severity denial of service vulnerability in Net-SNMP, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-89147 exists.

Affected product: Net-SNMP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89147/ (Markdown: https://insights.sbomify.com/CVE-2026-89147/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89147
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89147
- OSV: https://osv.dev/vulnerability/CVE-2026-89147

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89147/
Summaries are generated and may contain mistakes; the official description above is the record.