# CVE-2021-1309: Cisco Small Business RV Series Routers Link Layer Discovery Protocol Vulnerabilities

> An adjacent attacker can execute arbitrary code or cause a denial of service on Cisco Small Business RV Series Routers via LLDP vulnerabilities.

- **Severity:** High 7.4 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Apr 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-mqj7-w9r3-q3p2

## What is CVE-2021-1309?

CVE-2021-1309 is a high-severity memory corruption vulnerability in Cisco Small Business RV Series Router Firmware, published on 8 Apr 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Multiple vulnerabilities exist in the Link Layer Discovery Protocol (LLDP) implementation for Cisco Small Business RV Series Routers. An unauthenticated, adjacent attacker could execute arbitrary code or cause an affected router to leak system memory or reload. A memory leak or device reload would cause a denial of service (DoS) condition on an affected device. For more information about these vulnerabilities, see the Details section of this advisory. Note: LLDP is a Layer 2 protocol. To exploit these vulnerabilities, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-1309?

It affects 11 products.


Products: Cisco Rv132w Firmware, Cisco Rv134w Firmware, Cisco Rv160 Firmware, Cisco Rv160w Firmware, Cisco Rv260 Firmware, Cisco Rv260p Firmware, Cisco Rv260w Firmware, Cisco Rv340 Firmware, Cisco Rv340w Firmware, Cisco Rv345 Firmware, Cisco Rv345p Firmware.

## How do I fix CVE-2021-1309?

No fix has been published for CVE-2021-1309 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1309 being exploited?

There is no known exploitation of CVE-2021-1309 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Small Business RV Series Router Firmware

- [CVE-2018-0125](https://insights.sbomify.com/CVE-2018-0125/): Cisco VPN Routers Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2018-0127](https://insights.sbomify.com/CVE-2018-0127/): Missing authorization in Cisco RV132W and RV134W Wireless VPN Routers (critical 9.8)
- [CVE-2021-1251](https://insights.sbomify.com/CVE-2021-1251/): Cisco Small Business RV Series Routers Link Layer Discovery Protocol Vulnerabilities (high 7.4)
- [CVE-2021-1308](https://insights.sbomify.com/CVE-2021-1308/): Cisco Small Business RV Series Routers Link Layer Discovery Protocol Vulnerabilities (high 7.4)
- [CVE-2021-1287](https://insights.sbomify.com/CVE-2021-1287/): Command injection in Cisco Small Business RV Series Router Firmware (high 7.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1309 and fix it if it is affected.

What it is: CVE-2021-1309 is a high-severity memory corruption vulnerability in Cisco Small Business RV Series Router Firmware, published on 8 Apr 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-2021-1309 in the wild and no public exploit code.

Affected product: Cisco Small Business RV Series Router Firmware. 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-2021-1309/ (Markdown: https://insights.sbomify.com/CVE-2021-1309/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1309
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1309
- OSV: https://osv.dev/vulnerability/CVE-2021-1309

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-1309/
Summaries are generated and may contain mistakes; the official description above is the record.