CVE-2022-23645 is a medium-severity vulnerability classified as an out-of-bounds read (CWE-125) in the swtpm software, which is a TPM (Trusted Platform Module) emulator based on libtpms. swtpm provides TPM functionality through socket, character device, and Linux CUSE interfaces, enabling virtualized environments and software relying on TPM features to emulate hardware TPMs. The vulnerability affects swtpm versions prior to 0.5.3, versions from 0.6.0 up to but not including 0.6.2, and version 0.7.0. The root cause is an invalid hdrsize value in the blobheader of the TPM state representation. When swtpm attempts to parse a specially crafted TPM state blob with a malformed header, it performs an out-of-bounds read on the byte array representing the TPM state. This can cause the swtpm process to crash or fail to start because it cannot correctly interpret the TPM state data. Since TPM state is critical for TPM operation, this failure impacts availability of the TPM emulator service. There are no known workarounds, and the only remediation is upgrading to patched versions 0.5.3, 0.6.2, or 0.7.1 where the issue is fixed. No exploits have been reported in the wild to date. The vulnerability does not appear to allow arbitrary code execution or direct confidentiality or integrity breaches, but denial of TPM service could disrupt dependent systems or virtual machines relying on TPM functionality for security operations such as key storage, attestation, or secure boot.

For European organizations, the impact of this vulnerability primarily concerns environments that utilize TPM emulation via swtpm, such as virtualized infrastructures, cloud service providers, and enterprises using TPM-backed security features in virtual machines. The out-of-bounds read can cause swtpm to crash or fail to initialize, leading to TPM unavailability. This can disrupt security-critical operations including cryptographic key management, platform integrity verification, and secure boot processes that depend on TPM functionality. Organizations relying on TPM emulation for compliance, secure credential storage, or trusted computing may face operational interruptions or degraded security assurances. While the vulnerability does not directly expose sensitive data or allow privilege escalation, the denial of TPM service could indirectly weaken security postures or cause downtime in environments where TPM is integral. Given the lack of known exploits, the immediate risk is moderate, but unpatched systems remain vulnerable to potential future exploitation or accidental crashes triggered by malformed TPM state data.

To mitigate this vulnerability, European organizations should prioritize upgrading swtpm to versions 0.5.3, 0.6.2, or 0.7.1 as appropriate for their deployment. This is the only effective remediation since no workarounds exist. Organizations should audit their environments to identify all instances of swtpm, including those embedded in virtualization platforms or cloud infrastructure, and verify the version in use. Automated patch management tools can help ensure timely updates. Additionally, organizations should implement monitoring of swtpm processes and logs to detect crashes or failures indicative of malformed TPM state data. Where possible, restrict access to TPM state files and interfaces to trusted administrators and processes to reduce the risk of maliciously crafted state injection. For environments with high availability requirements, consider implementing redundancy or failover mechanisms for TPM emulation services to minimize disruption. Finally, maintain awareness of vendor advisories and community reports for any emerging exploits or additional mitigations.