CVE-2023-43634 | Config Partition Not Protected by Measured Boot
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”
Conclusion & alert: CVE-2023-43634 is rated Low Risk (37.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.16%).Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
Exploit prediction scoring system (EPSS) score for CVE-2023-43634
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).