# CVE-2020-25856: Memory corruption in Realtek RTL8195A Wi-Fi Module

> A stack buffer overflow in the Realtek RTL8195A Wi-Fi module allows remote code execution or denial of service via crafted WPA2 handshake packets.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:** 3 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9rrj-w544-7vw9

## What is CVE-2020-25856?

CVE-2020-25856 is a high-severity memory corruption vulnerability in Realtek RTL8195A Wi-Fi Module, published on 3 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The function DecWPA2KeyData() in the Realtek RTL8195A Wi-Fi Module prior to versions released in April 2020 (up to and excluding 2.08) does not validate the size parameter for an rtl_memcpy() operation, resulting in a stack buffer overflow which can be exploited for remote code execution or denial of service. An attacker can impersonate an Access Point and attack a vulnerable Wi-Fi client, by injecting a crafted packet into the WPA2 handshake. The attacker needs to know the network's PSK in order to exploit this.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2020-25856?

It affects 1 product.


Products: Realtek Rtl8195a Firmware.

## How do I fix CVE-2020-25856?

No fix has been published for CVE-2020-25856 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-25856 being exploited?

There is no known exploitation of CVE-2020-25856 in the wild and no public exploit code.

## Other vulnerabilities in Realtek RTL8195A Wi-Fi Module

- [CVE-2020-25854](https://insights.sbomify.com/CVE-2020-25854/): Memory corruption in Realtek RTL8195A Wi-Fi Module (high 8.1)
- [CVE-2020-25855](https://insights.sbomify.com/CVE-2020-25855/): Memory corruption in Realtek RTL8195A Wi-Fi Module (high 8.1)
- [CVE-2020-27301](https://insights.sbomify.com/CVE-2020-27301/): Memory corruption in n/a (high 8.0)
- [CVE-2020-27302](https://insights.sbomify.com/CVE-2020-27302/): Memory corruption in n/a (high 8.0)
- [CVE-2020-25853](https://insights.sbomify.com/CVE-2020-25853/): Memory corruption in Realtek RTL8195A Wi-Fi Module (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25856 and fix it if it is affected.

What it is: CVE-2020-25856 is a high-severity memory corruption vulnerability in Realtek RTL8195A Wi-Fi Module, published on 3 Feb 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-2020-25856 in the wild and no public exploit code.

Affected product: Realtek RTL8195A Wi-Fi Module. 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-2020-25856/ (Markdown: https://insights.sbomify.com/CVE-2020-25856/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25856
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25856
- OSV: https://osv.dev/vulnerability/CVE-2020-25856

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-25856/
Summaries are generated and may contain mistakes; the official description above is the record.