Edge Virtualization EngineOperating system · Linuxfoundation

CVE-2023-43631

HIGH · 8.8 CVSS v3.1 Published 2023-09-21
Fix available
A fix is available. Upgrade to 8.6.0 / 9.5.0 or later.
See remediation →
90/100
Remediation priority · Urgent
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In EVE-OS, the Pillar eve container checks for `/config/authorized_keys` on boot and enables SSH root login with those keys if present. Since the `/config` partition is mutable, unencrypted, and not included in the measured boot process (PCR values), an attacker can modify this file to add their own SSH key, gaining full root control without triggering the 'Unknown Update Detected' (UUD) mechanism or changing PCR values that would alert the measured boot system.

MitigationEnsure the `/config` partition is measured into the TPM PCR values (PCR13/PCR14) during boot so any modification to `authorized_keys` triggers measured boot alerts. Upgrade to versions where the config partition measurement has been properly implemented.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Edge Virtualization EngineOperating system
Affected:< 8.6.0>= 9.0.0, < 9.5.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check EVE-OS version
    Run 'cat /etc/eve-version' or check the EVE release version via the UI or 'grep -r version /opt/*' to identify the installed EVE-OS version
    Affected if The version is less than 8.6.0, or greater than or equal to 9.0.0 but less than 9.5.0
  2. Verify if /config/authorized_keys exists
    Check if the file /config/authorized_keys exists on the device. On EVE-OS, this is typically mounted from the CONFIG partition. You can inspect it by mounting the CONFIG partition or accessing it via the EVE CLI 'evectl' command
    Affected if The file /config/authorized_keys exists and contains one or more SSH public keys
  3. Confirm SSH root login is enabled
    Review the EVE-OS pillar container logs or configuration to verify that the Pillar service is configured to enable SSH root login based on /config/authorized_keys. Check pillar logs for 'authorized_keys' or 'ssh' related initialization messages
    Affected if SSH root login via authorized_keys is enabled in the EVE-OS pillar configuration
  4. Check if config partition is measured in TPM PCR
    Query the TPM PCR values (PCR13 and PCR14 are typically used for config measurements) using 'tpm2_pcrread' or similar tools to verify if the /config partition contents are included in the measured boot chain
    Affected if PCR13/PCR14 do not include measurements of the /config partition contents, meaning modifications to authorized_keys will not trigger measured boot alerts

You are affected if you are running a vulnerable EVE-OS version (< 8.6.0 or >= 9.0.0 to < 9.5.0), the /config/authorized_keys file exists with keys, SSH root login is enabled via this mechanism, and the /config partition is NOT measured into TPM PCR values.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.6.0 / 9.5.0 or later
Fixed in 8.6.09.5.0
Interim mitigation

Ensure the `/config` partition is measured into the TPM PCR values (PCR13/PCR14) during boot so any modification to `authorized_keys` triggers measured boot alerts. Upgrade to versions where the config partition measurement has been properly implemented.

Recommended fix High confidence

Upgrade to Edge Virtualization Engine version 8.6.0+ (8.x branch) or version 9.5.0+ (9.x branch)

  1. 1. Identify the current installed version of Edge Virtualization Engine using `eve version` or the EVE CLI tool
  2. 2. If running version < 8.6.0, upgrade to version 8.6.0 or later in the 8.x branch
  3. 3. If running version >= 9.0.0 and < 9.5.0, upgrade to version 9.5.0 or later in the 9.x branch
  4. 4. Verify the upgrade was successful by checking the new version number
  5. 5. After upgrade, verify that the /config partition is now properly measured by checking PCR13 or PCR14 values as appropriate for your EVE-OS version
  6. 6. Confirm that the measured boot mechanism now properly detects any unauthorized modifications to /config/authorized_keys
Caveat Review release notes for version 9.5.0 to check for any breaking changes between 9.0.0-9.4.x and 9.5.0, as well as between 8.x and 9.x branches

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Edge Virtualization Engine Scoped from the published advisory
  • Consultation10.0 h
  • Implementation32.0 h
  • Testing20.0 h
  • Review / QA10.0 h
72.0 hours of engineering $12,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-43631 in production — separate from our analysis above.

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What this is

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