# CVE-2020-25576: Unaligned memory access in rand_core

> Improper alignment handling in rand_core allows attackers to cause memory corruption, potentially leading to code execution or crashes.

- **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:** Yes
- **Published:** 14 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** AZL-46540, DEBIAN-CVE-2020-25576, GHSA-mmc9-pwm7-qj5w, RUSTSEC-2019-0035, UBUNTU-CVE-2020-25576

## What is CVE-2020-25576?

CVE-2020-25576 is a critical memory corruption vulnerability in n/a, published on 14 Sep 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 rand_core crate before 0.4.2 for Rust. Casting of byte slices to integer slices mishandles alignment constraints.

Weakness: CWE-704 (Incorrect Type Conversion or Cast)

## Which versions are affected by CVE-2020-25576?

5 open source packages ship an affected version, including rand_core. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rand_core` | crates.io | All versions | 0.3.1 |
| `rand_core` | crates.io | All versions | 0.3.1 |
| `rand_core` | crates.io | From 0.0.0-0 | 0.3.1, 0.4.2 |
| `rand_core` | crates.io | From 0.4.0 | 0.4.2 |
| `rand_core` | crates.io | From 0.4.0 | 0.4.2 |

Products: Rust-Random Rand.

## How do I fix CVE-2020-25576?

Upgrade rand_core to a fixed version for your release line: 0.3.1 or 0.4.2.

## Is CVE-2020-25576 being exploited?

There is no known exploitation of CVE-2020-25576 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25576 and fix it if it is affected.

What it is: CVE-2020-25576 is a critical memory corruption vulnerability in n/a, published on 14 Sep 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-2020-25576 in the wild and no public exploit code.

Affected packages and fixed versions:
- rand_core (crates.io): affected all versions; fixed in 0.3.1
- rand_core (crates.io): affected all versions; fixed in 0.3.1
- rand_core (crates.io): affected from 0.0.0-0; fixed in 0.3.1, 0.4.2
- rand_core (crates.io): affected from 0.4.0; fixed in 0.4.2
- rand_core (crates.io): affected from 0.4.0; fixed in 0.4.2

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-2020-25576/ (Markdown: https://insights.sbomify.com/CVE-2020-25576/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25576
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25576
- OSV: https://osv.dev/vulnerability/CVE-2020-25576

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-25576/
Summaries are generated and may contain mistakes; the official description above is the record.