# CVE-2021-37909: CHANGING Inc. TSSServiSignAdapter Windows Versions - Improper Input Validation

> Remote attackers can exploit improper input validation in the WriteRegistry function to rewrite the registry and execute arbitrary code.

- **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:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-7wg8-6xc4-8gfw

## What is CVE-2021-37909?

CVE-2021-37909 is a critical vulnerability in CHANGING Inc. TSSServiSignAdapter, published on 15 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

WriteRegistry function in TSSServiSign component does not filter and verify users’ input, remote attackers can rewrite to the registry without permissions thus perform hijack attacks to execute arbitrary code.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-37909?

It affects 1 product.


Products: Tssservisignadapter Project Tssservisignadapter.

## How do I fix CVE-2021-37909?

No fix has been published for CVE-2021-37909 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-37909 being exploited?

There is no known exploitation of CVE-2021-37909 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-37909 and fix it if it is affected.

What it is: CVE-2021-37909 is a critical vulnerability in CHANGING Inc. TSSServiSignAdapter, published on 15 Sep 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-2021-37909 in the wild and no public exploit code.

Affected product: CHANGING Inc. TSSServiSignAdapter. 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-2021-37909/ (Markdown: https://insights.sbomify.com/CVE-2021-37909/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37909
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37909
- OSV: https://osv.dev/vulnerability/CVE-2021-37909

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-37909/
Summaries are generated and may contain mistakes; the official description above is the record.