# CVE-2026-20048: Cisco NX-OS Software SNMP Denial of Service Vulnerability

> An authenticated remote attacker can cause a kernel panic and device reload by sending continuous SNMP queries to a specific MIB on Cisco Nexus ACI switches.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Feb 2026
- **Updated:** 25 Feb 2026
- **Also known as:** GHSA-c9vx-x9q2-ffx8

## What is CVE-2026-20048?

CVE-2026-20048 is a high-severity denial of service vulnerability in Cisco NX-OS System Software in ACI Mode, published on 25 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco Nexus 9000 Series Fabric Switches in ACI mode could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to improper processing when parsing SNMP requests. An attacker could exploit this vulnerability by continuously sending SNMP queries to a specific MIB of an affected device. A successful exploit could allow the attacker to cause a kernel panic on the device, resulting in a reload and a DoS condition.
Note: This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMPv1 or SNMPv2c, the attacker must have a valid read-only SNMP community string for the affected system. To exploit this vulnerability through SNMPv3, the attacker must have valid SNMP user credentials for the affected system.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value)

## Which versions are affected by CVE-2026-20048?


## How do I fix CVE-2026-20048?

No fix has been published for CVE-2026-20048 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20048 being exploited?

There is no known exploitation of CVE-2026-20048 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20048 and fix it if it is affected.

What it is: CVE-2026-20048 is a high-severity denial of service vulnerability in Cisco NX-OS System Software in ACI Mode, published on 25 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-20048 in the wild and no public exploit code.

Affected product: Cisco NX-OS System Software in ACI Mode. 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-2026-20048/ (Markdown: https://insights.sbomify.com/CVE-2026-20048/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20048
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20048
- OSV: https://osv.dev/vulnerability/CVE-2026-20048

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20048/
Summaries are generated and may contain mistakes; the official description above is the record.