# CVE-2021-1376: Cisco IOS XE Software Fast Reload Vulnerabilities

> Authenticated local attackers can bypass secure boot checks to execute arbitrary code or unsigned binaries on Cisco Catalyst switches.

- **Severity:** Medium 6.7 (`CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Mar 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-pjh3-48qc-pm5c

## What is CVE-2021-1376?

CVE-2021-1376 is a medium-severity vulnerability in Cisco Ios Xe, published on 24 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Multiple vulnerabilities in the fast reload feature of Cisco IOS XE Software running on Cisco Catalyst 3850, Cisco Catalyst 9300, and Cisco Catalyst 9300L Series Switches could allow an authenticated, local attacker to either execute arbitrary code on the underlying operating system, install and boot a malicious software image, or execute unsigned binaries on an affected device. These vulnerabilities are due to improper checks performed by system boot routines. To exploit these vulnerabilities, the attacker would need privileged access to the CLI of the device. A successful exploit could allow the attacker to either execute arbitrary code on the underlying operating system or execute unsigned code and bypass the image verification check part of the secure boot process. For more information about these vulnerabilities, see the Details section of this advisory.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2021-1376?

It affects 1 product.


Products: Cisco Ios Xe.

## How do I fix CVE-2021-1376?

No fix has been published for CVE-2021-1376 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1376 being exploited?

There is no known exploitation of CVE-2021-1376 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios Xe

- [CVE-2023-20198](https://insights.sbomify.com/CVE-2023-20198/): Cisco IOS XE Web UI Privilege Escalation (critical 10.0, exploited in the wild)
- [CVE-2018-0151](https://insights.sbomify.com/CVE-2018-0151/): Cisco IOS Software and Cisco IOS XE Software Quality of Service Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2023-20273](https://insights.sbomify.com/CVE-2023-20273/): Cisco IOS XE Web UI Command Injection (high 7.2, exploited in the wild)
- [CVE-2025-20188](https://insights.sbomify.com/CVE-2025-20188/): Hardcoded credentials in Cisco IOS XE Software (critical 10.0)
- [CVE-2021-34770](https://insights.sbomify.com/CVE-2021-34770/): Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1376 and fix it if it is affected.

What it is: CVE-2021-1376 is a medium-severity vulnerability in Cisco Ios Xe, published on 24 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-1376 in the wild and no public exploit code.

Affected product: Cisco Ios Xe. 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-2021-1376/ (Markdown: https://insights.sbomify.com/CVE-2021-1376/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1376
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1376
- OSV: https://osv.dev/vulnerability/CVE-2021-1376

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1376/
Summaries are generated and may contain mistakes; the official description above is the record.