# CVE-2025-4878: Libssh: use of uninitialized variable in privatekey_from_file()

> An attacker can trigger heap corruption or signing failures in libssh by providing a non-existent private key file, potentially leading to code execution or denial of service.

- **Severity:** Low 3.6 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Jul 2025
- **Updated:** 1 Sep 2026
- **Also known as:** AZL-65643, AZL-65646, BELL-CVE-2025-4878, DEBIAN-CVE-2025-4878, GHSA-q2fw-m52x-w593, UBUNTU-CVE-2025-4878

## What is CVE-2025-4878?

CVE-2025-4878 is a low-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 22 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was found in libssh, where an uninitialized variable exists under certain conditions in the privatekey_from_file() function. This flaw can be triggered if the file specified by the filename doesn't exist and may lead to possible signing failures or heap corruption.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-4878?


## How do I fix CVE-2025-4878?

Apply the vendor's patch.

## Is CVE-2025-4878 being exploited?

There is no known exploitation of CVE-2025-4878 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-4878 and fix it if it is affected.

What it is: CVE-2025-4878 is a low-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 22 Jul 2025. 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-2025-4878 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2025-4878/ (Markdown: https://insights.sbomify.com/CVE-2025-4878/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-4878
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-4878
- OSV: https://osv.dev/vulnerability/CVE-2025-4878

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-4878/
Summaries are generated and may contain mistakes; the official description above is the record.