# CVE-2020-36284: Weak cryptography in n/a

> Attackers can bypass payment verification in Union Pay Android apps by exploiting a null secret key in MAC generation, allowing free purchases.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Apr 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vx7r-7h24-rm89

## What is CVE-2020-36284?

CVE-2020-36284 is a high-severity vulnerability in n/a, published on 6 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Union Pay up to 3.4.93.4.9, for android, contains a CWE-347: Improper Verification of Cryptographic Signature vulnerability, allows attackers to shop for free in merchants' websites and mobile apps, via a crafted authentication code (MAC) which is generated based on a secret key which is NULL.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2020-36284?

It affects 1 product.


Products: Unionpayintl Union Pay.

## How do I fix CVE-2020-36284?

No fix has been published for CVE-2020-36284 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-36284 being exploited?

There is no known exploitation of CVE-2020-36284 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-23533](https://insights.sbomify.com/CVE-2020-23533/): Weak cryptography in n/a (high 7.5)
- [CVE-2020-36285](https://insights.sbomify.com/CVE-2020-36285/): Weak cryptography in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-36284 and fix it if it is affected.

What it is: CVE-2020-36284 is a high-severity vulnerability in n/a, published on 6 Apr 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-2020-36284 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-2020-36284/ (Markdown: https://insights.sbomify.com/CVE-2020-36284/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-36284
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-36284
- OSV: https://osv.dev/vulnerability/CVE-2020-36284

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-36284/
Summaries are generated and may contain mistakes; the official description above is the record.