# CVE-2021-34947: NETGEAR R7800 net-cgi Out-Of-Bounds Write Remote Code Execution Vulnerability

> Network-adjacent attackers can execute arbitrary code as root on NETGEAR R7800 routers via an out-of-bounds write in net-cgi.

- **Severity:** High 8.8 (`CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 7 May 2024
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-jj28-565j-58r3

## What is CVE-2021-34947?

CVE-2021-34947 is a high-severity memory corruption vulnerability in Netgear D7800 Firmware, published on 7 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

NETGEAR R7800 net-cgi Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R7800 routers. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the parsing of the soap_block_table file. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated data structure. An attacker can leverage this vulnerability to execute code in the context of root.
. Was ZDI-CAN-13055.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-34947?

It affects 41 products.


Products: Netgear D7800 Firmware, Netgear Ex2700 Firmware, Netgear Ex6100 Firmware, Netgear Ex6150 Firmware, Netgear Ex6200 Firmware, Netgear Ex6250 Firmware, Netgear Ex6400 Firmware, Netgear Ex6400v2 Firmware, Netgear Ex6410 Firmware, Netgear Ex6420 Firmware, Netgear Ex6500v1 Firmware, Netgear Ex7300 Firmware, Netgear Ex7300v2 Firmware, Netgear Ex7320 Firmware, Netgear Ex7700 Firmware, Netgear Ex8000 Firmware, Netgear Lbr1020 Firmware, Netgear Lbr20 Firmware, Netgear R6700ax Firmware, Netgear R7800 Firmware and 21 more.

## How do I fix CVE-2021-34947?

No fix has been published for CVE-2021-34947 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34947 being exploited?

There is no known exploitation of CVE-2021-34947 in the wild and no public exploit code.

## Other vulnerabilities in Netgear D7800 Firmware

- [CVE-2021-45618](https://insights.sbomify.com/CVE-2021-45618/): Command injection in n/a (critical 9.6)
- [CVE-2022-27641](https://insights.sbomify.com/CVE-2022-27641/): Integer overflow in R6700v3 (high 8.8)
- [CVE-2020-26909](https://insights.sbomify.com/CVE-2020-26909/): Command injection in n/a (high 8.8)
- [CVE-2018-21202](https://insights.sbomify.com/CVE-2018-21202/): Memory corruption in n/a (high 8.8)
- [CVE-2018-21204](https://insights.sbomify.com/CVE-2018-21204/): Memory corruption in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34947 and fix it if it is affected.

What it is: CVE-2021-34947 is a high-severity memory corruption vulnerability in Netgear D7800 Firmware, published on 7 May 2024. 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-2021-34947 in the wild and no public exploit code.

Affected product: Netgear D7800 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-2021-34947/ (Markdown: https://insights.sbomify.com/CVE-2021-34947/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34947
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34947
- OSV: https://osv.dev/vulnerability/CVE-2021-34947

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34947/
Summaries are generated and may contain mistakes; the official description above is the record.