# CVE-2021-43393: Security feature bypass in n/a

> Attackers can bypass signature verification in STMicroelectronics Java Card secure elements, compromising the integrity of cryptographic operations.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Mar 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-94rv-67rm-q3v8

## What is CVE-2021-43393?

CVE-2021-43393 is a medium-severity vulnerability in n/a, published on 4 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

STMicroelectronics STSAFE-J 1.1.4, J-SAFE3 1.2.5, and J-SIGN sometimes allow attackers to abuse signature verification. This is associated with the ECDSA signature algorithm on the Java Card J-SAFE3 and STSAFE-J platforms exposing a 3.0.4 Java Card API. It is exploitable for STSAFE-J in closed configuration and J-SIGN (when signature verification is activated) but not for J-SAFE3 EPASS BAC and EAC products. It might also impact other products based on the J-SAFE-3 Java Card platform.

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

## Which versions are affected by CVE-2021-43393?

It affects 2 products.


Products: St J-Safe3 Firmware, St Stsafe-J Firmware.

## How do I fix CVE-2021-43393?

No fix has been published for CVE-2021-43393 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43393 being exploited?

There is no known exploitation of CVE-2021-43393 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-43392](https://insights.sbomify.com/CVE-2021-43392/): Information disclosure in n/a (medium 6.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43393 and fix it if it is affected.

What it is: CVE-2021-43393 is a medium-severity vulnerability in n/a, published on 4 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43393 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-2021-43393/ (Markdown: https://insights.sbomify.com/CVE-2021-43393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43393
- OSV: https://osv.dev/vulnerability/CVE-2021-43393

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43393/
Summaries are generated and may contain mistakes; the official description above is the record.