# CVE-2021-29294: Null dereference in n/a

> A remote attacker can cause a denial of service on the D-Link DSL-2740R router via a crafted POST request, but the device is end-of-life and will not be patched.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-4gpq-jpqc-j6v2

## What is CVE-2021-29294?

CVE-2021-29294 is a high-severity vulnerability in n/a, published on 10 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Null Pointer Dereference vulnerability exists in D-Link DSL-2740R UK_1.01, which could let a remove malicious user cause a denial of service via the send_hnap_unauthorized function. It could be triggered by sending crafted POST request to /HNAP1/. NOTE: The DSL-2740R and all hardware revisions are considered End of Life and as such this issue will not be patched

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-29294?

It affects 1 product.


Products: Dlink Dsl-2740r Firmware.

## How do I fix CVE-2021-29294?

No fix has been published for CVE-2021-29294 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-29294 being exploited?

There is no known exploitation of CVE-2021-29294 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-7027](https://insights.sbomify.com/CVE-2026-7027/): D-Link DSL-2740R Wireless Setup Section cross site scripting (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-29294 and fix it if it is affected.

What it is: CVE-2021-29294 is a high-severity vulnerability in n/a, published on 10 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-29294 in the wild and no public exploit code.

Affected product: n/a. 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-2021-29294/ (Markdown: https://insights.sbomify.com/CVE-2021-29294/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-29294
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-29294
- OSV: https://osv.dev/vulnerability/CVE-2021-29294

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-29294/
Summaries are generated and may contain mistakes; the official description above is the record.