# CVE-2021-31802: Memory corruption in n/a

> A heap-based buffer overflow in NETGEAR R7000 routers allows unauthenticated attackers on the local network to execute arbitrary code as root via a crafted HTTP request.

- **Severity:** High 8.8 (`CVSS:3.1/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:** 26 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-89v8-28p6-p87r

## What is CVE-2021-31802?

CVE-2021-31802 is a high-severity memory corruption vulnerability in Netgear R7000 Firmware, published on 26 Apr 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

NETGEAR R7000 1.0.11.116 devices have a heap-based Buffer Overflow that is exploitable from the local network without authentication. The vulnerability exists within the handling of an HTTP request. An attacker can leverage this to execute code as root. The problem is that a user-provided length value is trusted during a backup.cgi file upload. The attacker must add a \n before the Content-Length header.

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

## Which versions are affected by CVE-2021-31802?

It affects 1 product.


Products: Netgear R7000 Firmware.

## How do I fix CVE-2021-31802?

No fix has been published for CVE-2021-31802 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31802 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-31802 exists.

Public exploit code:

- Netgear R7000 backup.cgi Heap Overflow RCE (metasploit)

## Other vulnerabilities in Netgear R7000 Firmware

- [CVE-2022-37235](https://insights.sbomify.com/CVE-2022-37235/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-34977](https://insights.sbomify.com/CVE-2021-34977/): Auth bypass in R7000 (high 8.8)
- [CVE-2024-35520](https://insights.sbomify.com/CVE-2024-35520/): Command injection in n/a (high 8.4)
- [CVE-2022-37234](https://insights.sbomify.com/CVE-2022-37234/): Memory corruption in n/a (high 7.8)
- [CVE-2019-20758](https://insights.sbomify.com/CVE-2019-20758/): Memory corruption in n/a (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31802 and fix it if it is affected.

What it is: CVE-2021-31802 is a high-severity memory corruption vulnerability in Netgear R7000 Firmware, published on 26 Apr 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-31802 exists.

Affected product: Netgear R7000 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-2021-31802/ (Markdown: https://insights.sbomify.com/CVE-2021-31802/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31802
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31802
- OSV: https://osv.dev/vulnerability/CVE-2021-31802

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31802/
Summaries are generated and may contain mistakes; the official description above is the record.