# CVE-2020-5523: Weak cryptography in 'MyPallete' and some of the Android banking applications that use 'MyPallete'

> Man-in-the-middle attackers can spoof servers and steal sensitive data from Android banking apps using MyPallete due to improper X.509 certificate validation.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/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:** 28 Jan 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-qrwh-wc9j-x9cj

## What is CVE-2020-5523?

CVE-2020-5523 is a high-severity vulnerability in NTT Data Corporation 'MyPallete' and some of the Android banking applications that use 'MyPallete', published on 28 Jan 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Android App 'MyPallete' and some of the Android banking applications based on 'MyPallete' do not verify X.509 certificates from servers, and also do not properly validate certificates with host-mismatch, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2020-5523?

It affects 9 products.


Products: 77bank 77 Bank, Ashikagabank Ashigin, Hokkaidobank Dogin, Hokugin Hokuriku Bank Portal, Naganobank Nagagin, Nttdata Mypallete, Shikokubank Shikoku Bank, Sihd-Bk Ikeda Senshu Bank, Tohoku-Bank Tougin.

## How do I fix CVE-2020-5523?

No fix has been published for CVE-2020-5523 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-5523 being exploited?

There is no known exploitation of CVE-2020-5523 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5523 and fix it if it is affected.

What it is: CVE-2020-5523 is a high-severity vulnerability in NTT Data Corporation 'MyPallete' and some of the Android banking applications that use 'MyPallete', published on 28 Jan 2020. 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-2020-5523 in the wild and no public exploit code.

Affected product: NTT Data Corporation 'MyPallete' and some of the Android banking applications that use 'MyPallete'. 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-2020-5523/ (Markdown: https://insights.sbomify.com/CVE-2020-5523/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5523
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5523
- OSV: https://osv.dev/vulnerability/CVE-2020-5523

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-5523/
Summaries are generated and may contain mistakes; the official description above is the record.