# CVE-2023-43631: SSH as Root Unlockable Without Triggering Measured Boot

> Attackers can gain root SSH access by modifying an unprotected config file, bypassing measured boot integrity checks on EVE OS devices.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 21 Sep 2023
- **Updated:** 24 Sep 2024
- **Also known as:** GHSA-3mq9-xhgq-r7gj, GO-2026-4418

## What is CVE-2023-43631?

CVE-2023-43631 is a high-severity authentication bypass vulnerability in EVE OS, published on 21 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

On boot, the Pillar eve container checks for the existence and content of
“/config/authorized_keys”.

If the file is present, and contains a supported public key, the container will go on to open
port 22 and enable sshd with the given keys as the authorized keys for root login.

An attacker could easily add their own keys and gain full control over the system without
triggering the “measured boot” mechanism implemented by EVE OS, and without marking
the device as “UUD” (“Unknown Update Detected”).

This is because the “/config” partition is not protected by “measured boot”, it is mutable, and
it is not encrypted in any way.

An attacker can gain full control over the device without changing the PCR values, thus not
triggering the “measured boot” mechanism, and having full access to the vault.

Note:

This issue was partially fixed in these commits (after disclosure to Zededa), where the config
partition measurement was added to PCR13:

• aa3501d6c57206ced222c33aea15a9169d629141

• 5fef4d92e75838cc78010edaed5247dfbdae1889.

This issue was made viable in version 9.0.0 when the calculation was moved to PCR14 but it was not included in the measured boot.

Weakness: CWE-922 (Insecure Storage of Sensitive Information), CWE-522 (Insufficiently Protected Credentials)

## Which versions are affected by CVE-2023-43631?

3 open source packages ship an affected version, including github.com/lf-edge/eve. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/lf-edge/eve` | Go | All versions | 0.0.0-20220708121648-5fef4d92e758 |
| `github.com/lf-edge/eve` | Go | All versions | 0.0.0-20220708121648-5fef4d92e758 |
| `github.com/lf-edge/eve` | Go | All versions | 0.0.0-20220708121648-5fef4d92e758 |

Products: Linuxfoundation Edge Virtualization Engine.

## How do I fix CVE-2023-43631?

Upgrade github.com/lf-edge/eve to 0.0.0-20220708121648-5fef4d92e758 or later.

## Is CVE-2023-43631 being exploited?

There is no known exploitation of CVE-2023-43631 in the wild and no public exploit code.

## Other vulnerabilities in EVE OS

- [CVE-2023-43632](https://insights.sbomify.com/CVE-2023-43632/): Freely Allocate Buffer on The Stack With Data From Socket (critical 9.0)
- [CVE-2023-43630](https://insights.sbomify.com/CVE-2023-43630/): Config Partition Not Measured From 2 Fronts (high 8.8)
- [CVE-2023-43635](https://insights.sbomify.com/CVE-2023-43635/): Vault Key Sealed With SHA1 PCRs (high 8.8)
- [CVE-2023-43636](https://insights.sbomify.com/CVE-2023-43636/): Rootfs Not Protected (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-43631 and fix it if it is affected.

What it is: CVE-2023-43631 is a high-severity authentication bypass vulnerability in EVE OS, published on 21 Sep 2023. 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-2023-43631 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/lf-edge/eve (Go): affected all versions; fixed in 0.0.0-20220708121648-5fef4d92e758
- github.com/lf-edge/eve (Go): affected all versions; fixed in 0.0.0-20220708121648-5fef4d92e758
- github.com/lf-edge/eve (Go): affected all versions; fixed in 0.0.0-20220708121648-5fef4d92e758

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-2023-43631/ (Markdown: https://insights.sbomify.com/CVE-2023-43631/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-43631
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-43631
- OSV: https://osv.dev/vulnerability/CVE-2023-43631

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-43631/
Summaries are generated and may contain mistakes; the official description above is the record.