# CVE-2020-29557: D-Link DIR-825 R1 Devices Buffer Overflow

> A buffer overflow in the web interface allows attackers to achieve pre-authentication remote code execution on D-Link DIR-825 R1 devices.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Jan 2021
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-x5v2-fv6f-w5rh

## What is CVE-2020-29557?

CVE-2020-29557 is a critical memory corruption vulnerability in n/a, published on 29 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered on D-Link DIR-825 R1 devices through 3.0.1 before 2020-11-20. A buffer overflow in the web interface allows attackers to achieve pre-authentication remote code execution.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2020-29557?

It affects 1 product.


Products: Dlink Dir-825 R1 Firmware.

## How do I fix CVE-2020-29557?

No fix has been published for CVE-2020-29557 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 May 2022.

## Is CVE-2020-29557 being exploited?

Yes. Attackers have exploited CVE-2020-29557 in the wild since at least 3 Nov 2021.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-29557 and fix it if it is affected.

What it is: CVE-2020-29557 is a critical memory corruption vulnerability in n/a, published on 29 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2020-29557 in the wild since at least 3 Nov 2021.

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-2020-29557/ (Markdown: https://insights.sbomify.com/CVE-2020-29557/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-29557
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-29557
- OSV: https://osv.dev/vulnerability/CVE-2020-29557

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-29557/
Summaries are generated and may contain mistakes; the official description above is the record.