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EveOperating system · Lfedge

CVE-2023-43634

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
When sealing/unsealing the “vault” key, a list of PCRs is used, which defines which PCRs are used. In a previous project, CYMOTIVE found that the configuration is not protected by the secure boot, and in response Zededa implemented measurements on the config partition that was mapped to PCR 13. In that process, PCR 13 was added to the list of PCRs that seal/unseal the key. In commit “56e589749c6ff58ded862d39535d43253b249acf”, the config partition measurement moved from PCR 13 to PCR 14, but PCR 14 was not added to the list of PCRs that seal/unseal the key. This change makes the measurement of PCR 14 effectively redundant as it would not affect the sealing/unsealing of the key. An attacker could modify the config partition without triggering the measured boot, this could result in the attacker gaining full control over the device with full access to the contents of the encrypted “vault”

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

When Zededa migrated config partition measurement from PCR 13 to PCR 14 in commit 56e589749c6ff58ded862d39535d43253b249acf, they failed to add PCR 14 to the list of PCRs used for sealing/unsealing the TPM-protected vault key. This disconnect means the config partition measurement to PCR 14 is ignored by the TPM sealing policy, allowing attackers to modify the config partition without invalidating the sealed key, potentially gaining full device control and access to the encrypted vault.

MitigationAdd PCR 14 to the list of PCRs used when sealing/unsealing the vault key to ensure the config partition measurement actually protects the TPM-based key binding.

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
EveOperating 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. Determine the installed Eve version
    Run 'eve version' or check /etc/eve-version to get the exact version number of Lfedge Eve installed on the device
    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 TPM vault encryption is in use
    Check if the device uses TPM-protected vault key storage. This is typically indicated by the presence of a TPM-backed encryption configuration in /var/lib/eve/encryption.conf or similar vault configuration files
    Affected if TPM-based key sealing is enabled and the system uses the TPM to protect the vault key
  3. Inspect the TPM sealing policy PCR list
    Examine the TPM sealing configuration to identify which PCRs are included in the sealing policy. This may be found in TPM-related configuration files or by querying the TPM seal object using tpm2 tools if available
    Affected if The sealing policy includes PCR 13 but does NOT include PCR 14 in the list of PCRs used for sealing/unsealing the vault key
  4. Confirm PCR 14 measurement is active for config partition
    Check whether the system is measuring the config partition to PCR 14, which can be verified by inspecting TPM PCR logs or event logs that record PCR 14 extensions
    Affected if PCR 14 measurements are being performed for the config partition but those measurements are not part of the TPM sealing policy

A user is affected if their Eve version falls within the vulnerable range and the TPM sealing policy includes PCR 13 but omits PCR 14 while the config partition is being measured to PCR 14.

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

Add PCR 14 to the list of PCRs used when sealing/unsealing the vault key to ensure the config partition measurement actually protects the TPM-based key binding.

Recommended fix High confidence

Eve OS 8.6.0 or Eve OS 9.5.0

  1. Locate the PCR list configuration in the codebase that controls sealing/unsealing of the vault key
  2. Add PCR 14 to the list of PCRs used for sealing/unsealing the vault key, alongside the existing PCRs (likely PCR 13)
  3. Rebuild the Eve OS image with the corrected PCR configuration
  4. Re-deploy the updated image to affected devices to ensure the config partition measurement properly protects the sealing/unsealing mechanism

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

Fix this in Eve Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
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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-2023-43634 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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