# CVE-2020-35865: os_str_bytes relies on undefined behavior of `char::from_u32_unchecked`

> The os_str_bytes crate mishandles character conversion, potentially causing unexpected behavior in Rust applications using it.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-q948-x8rf-888m, RUSTSEC-2020-0012

## What is CVE-2020-35865?

CVE-2020-35865 is a high-severity vulnerability in n/a, published on 31 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in the os_str_bytes crate before 2.0.0 for Rust. It has false expectations about char::from_u32_unchecked behavior.

## Which versions are affected by CVE-2020-35865?

3 open source packages ship an affected version, including os_str_bytes. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `os_str_bytes` | crates.io | All versions | 2.0.0 |
| `os_str_bytes` | crates.io | All versions | 2.0.0 |
| `os_str_bytes` | crates.io | From 0.0.0-0 | 2.0.0 |

Products: Os Str Bytes Project Os Str Bytes.

## How do I fix CVE-2020-35865?

Upgrade os_str_bytes to 2.0.0 or later.

## Is CVE-2020-35865 being exploited?

There is no known exploitation of CVE-2020-35865 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-35865 and fix it if it is affected.

What it is: CVE-2020-35865 is a high-severity vulnerability in n/a, published on 31 Dec 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-2020-35865 in the wild and no public exploit code.

Affected packages and fixed versions:
- os_str_bytes (crates.io): affected all versions; fixed in 2.0.0
- os_str_bytes (crates.io): affected all versions; fixed in 2.0.0
- os_str_bytes (crates.io): affected from 0.0.0-0; fixed in 2.0.0

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-2020-35865/ (Markdown: https://insights.sbomify.com/CVE-2020-35865/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-35865
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-35865
- OSV: https://osv.dev/vulnerability/CVE-2020-35865

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-35865/
Summaries are generated and may contain mistakes; the official description above is the record.