Executive Summary

This vulnerability exists in Vanetza, an open-source implementation of the ETSI C-ITS protocol suite. In versions 26.02 and earlier, there is a denial-of-service issue in the cryptographic verification pipeline. Specifically, when processing incoming V2X messages, the ASN.1 decoder accepts packets as syntactically valid even if they contain semantic violations in certain fields, such as an invalid Psid (Provider Service Identifier) sub-type.

The problem arises because these semantic constraints are only enforced later during OER re-encoding. When the system attempts to re-encode the signing certificate to calculate a message hash for cryptographic verification, it detects the semantic violation and raises an uncaught exception. This causes the process to terminate immediately, resulting in a denial-of-service condition.

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Impact Analysis

This vulnerability can cause a denial-of-service (DoS) condition in systems using Vanetza for V2X message processing. An attacker can craft a malicious packet with an invalid Psid sub-type that triggers an uncaught exception during cryptographic verification, causing the process to terminate unexpectedly.

As a result, the affected system may become unavailable or stop processing messages, potentially disrupting communication in vehicular networks that rely on Vanetza for secure message verification.

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Mitigation Strategies

The vulnerability is fixed with commit e1a2e2709210d309458c3d77f98d50dec26c0df0. Immediate mitigation involves updating Vanetza to a version that includes this fix.

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Compliance Impact

The vulnerability causes a denial-of-service condition in the Vanetza V2X communication library by allowing crafted packets with malformed certificates to crash the process during cryptographic verification.

While the CVE description and resources do not explicitly mention compliance with standards such as GDPR or HIPAA, the primary impact is service unavailability due to denial-of-service.

Such service disruptions could indirectly affect compliance with regulations that require availability and integrity of systems processing sensitive data, but no direct link or impact on data privacy or protection requirements is stated.

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Detection Guidance

This vulnerability manifests as a denial-of-service condition caused by the Vanetza process terminating unexpectedly when processing crafted V2X messages with malformed certificates. Detection can focus on monitoring for unexpected crashes or terminations of the Vanetza service.

To detect exploitation attempts or the presence of malformed packets on your network, you can monitor network traffic for suspicious V2X messages containing certificates with invalid Provider Service Identifier (Psid) subtypes.

Since the vulnerability triggers a std::runtime_error during certificate re-encoding, system logs or application logs showing such exceptions or process crashes can be indicators.

• Use system service monitoring commands to detect Vanetza process crashes, for example: `systemctl status vanetza` or `journalctl -u vanetza` on Linux systems.
• Monitor application logs for uncaught exceptions or termination messages related to certificate encoding errors.
• Capture and analyze network traffic with tools like tcpdump or Wireshark filtering for V2X protocol messages to identify malformed certificates. Example command: `tcpdump -i <interface> -w capture.pcap` followed by analysis in Wireshark.
• If you have access to the Vanetza source or debugging environment, consider adding logging around the certificate verification and encoding functions to detect when invalid Psid subtypes are processed.

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