# CVE-2020-35684: Memory corruption in n/a

> Attackers can trigger out-of-bounds reads or writes in TCP packet parsing by manipulating IP payload size fields, potentially causing crashes or information disclosure.

- **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:** 19 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-748v-rhfv-4hm6

## What is CVE-2020-35684?

CVE-2020-35684 is a high-severity memory corruption vulnerability in n/a, published on 19 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in HCC Nichestack 3.0. The code that parses TCP packets relies on an unchecked value of the IP payload size (extracted from the IP header) to compute the length of the TCP payload within the TCP checksum computation function. When the IP payload size is set to be smaller than the size of the IP header, the TCP checksum computation function may read out of bounds (a low-impact write-out-of-bounds is also possible).

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-35684?

It affects 3 products.


Products: Hcc-Embedded Nichestack, Siemens Sentron 3wa Com190 Firmware, Siemens Sentron 3wl Com35 Firmware.

## How do I fix CVE-2020-35684?

No fix has been published for CVE-2020-35684 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-35684 being exploited?

There is no known exploitation of CVE-2020-35684 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-35685](https://insights.sbomify.com/CVE-2020-35685/): Weak cryptography in n/a (critical 9.1)
- [CVE-2020-35683](https://insights.sbomify.com/CVE-2020-35683/): Memory corruption in n/a (high 7.5)
- [CVE-2021-27565](https://insights.sbomify.com/CVE-2021-27565/): Denial of service in n/a (high 7.5)
- [CVE-2021-31227](https://insights.sbomify.com/CVE-2021-31227/): Memory corruption in n/a (high 7.5)
- [CVE-2021-31228](https://insights.sbomify.com/CVE-2021-31228/): Weak cryptography in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-35684 and fix it if it is affected.

What it is: CVE-2020-35684 is a high-severity memory corruption vulnerability in n/a, published on 19 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-2020-35684 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-2020-35684/ (Markdown: https://insights.sbomify.com/CVE-2020-35684/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-35684
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-35684
- OSV: https://osv.dev/vulnerability/CVE-2020-35684

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-35684/
Summaries are generated and may contain mistakes; the official description above is the record.