# CVE-2020-25578: Information disclosure in FreeBSD

> Local attackers can read uninitialized kernel stack bytes via specific file systems, potentially leaking sensitive information.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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:** 26 Mar 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v45v-x46m-37q7

## What is CVE-2020-25578?

CVE-2020-25578 is a medium-severity vulnerability in Freebsd Freebsd, published on 26 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In FreeBSD 12.2-STABLE before r368969, 11.4-STABLE before r369047, 12.2-RELEASE before p3, 12.1-RELEASE before p13 and 11.4-RELEASE before p7 several file systems were not properly initializing the d_off field of the dirent structures returned by VOP_READDIR. In particular, tmpfs(5), smbfs(5), autofs(5) and mqueuefs(5) were failing to do so. As a result, eight uninitialized kernel stack bytes may be leaked to userspace by these file systems.

Weakness: CWE-665 (Improper Initialization)

## Which versions are affected by CVE-2020-25578?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2020-25578?

No fix has been published for CVE-2020-25578 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-25578 being exploited?

There is no known exploitation of CVE-2020-25578 in the wild and no public exploit code.

Public exploit code:

- CVE-2020-25578 and CVE-2020-25579: Some FreeBSD info leak bugs I found in 2020. (github_poc): https://github.com/farazsth98/freebsd-dirent-info-leak-bugs

## Other vulnerabilities in Freebsd Freebsd

- [CVE-2018-17160](https://insights.sbomify.com/CVE-2018-17160/): Memory corruption in FreeBSD (critical 10.0)
- [CVE-2014-3954](https://insights.sbomify.com/CVE-2014-3954/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-4304](https://insights.sbomify.com/CVE-2006-4304/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-0226](https://insights.sbomify.com/CVE-2006-0226/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0002](https://insights.sbomify.com/CVE-2004-0002/): Denial of service in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25578 and fix it if it is affected.

What it is: CVE-2020-25578 is a medium-severity vulnerability in Freebsd Freebsd, published on 26 Mar 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-2020-25578 in the wild and no public exploit code.

Affected product: Freebsd Freebsd. 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-2020-25578/ (Markdown: https://insights.sbomify.com/CVE-2020-25578/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25578
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25578
- OSV: https://osv.dev/vulnerability/CVE-2020-25578

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-25578/
Summaries are generated and may contain mistakes; the official description above is the record.