# CVE-2021-36219: Use after free in n/a

> An attacker can compromise enclave integrity by triggering a use-after-free in ECALL 14, potentially leading to code execution within the trusted environment.

- **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:** 27 Sep 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9x89-2rj7-6392

## What is CVE-2021-36219?

CVE-2021-36219 is a critical use after free vulnerability in n/a, published on 27 Sep 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 SKALE sgxwallet 1.58.3. The provided input for ECALL 14 triggers a branch in trustedEcdsaSign that frees a non-initialized pointer from the stack. An attacker can chain multiple enclave calls to prepare a stack that contains a valid address. This address is then freed, resulting in compromised integrity of the enclave. This was resolved after v1.58.3 and not reproducible in sgxwallet v1.77.0.

Weakness: CWE-824 (Access of Uninitialized Pointer)

## Which versions are affected by CVE-2021-36219?

It affects 1 product.


Products: Skale Sgxwallet.

## How do I fix CVE-2021-36219?

No fix has been published for CVE-2021-36219 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-36219 being exploited?

There is no known exploitation of CVE-2021-36219 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2023-36198](https://insights.sbomify.com/CVE-2023-36198/): Memory corruption in n/a (high 7.5)
- [CVE-2023-36199](https://insights.sbomify.com/CVE-2023-36199/): Null dereference in n/a (high 7.5)
- [CVE-2021-36218](https://insights.sbomify.com/CVE-2021-36218/): An issue was discovered in SKALE sgxwallet 1.58.3. (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36219 and fix it if it is affected.

What it is: CVE-2021-36219 is a critical use after free vulnerability in n/a, published on 27 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-2021-36219 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-2021-36219/ (Markdown: https://insights.sbomify.com/CVE-2021-36219/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36219
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36219
- OSV: https://osv.dev/vulnerability/CVE-2021-36219

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36219/
Summaries are generated and may contain mistakes; the official description above is the record.