Executive Summary

CVE-2025-12899 is a type confusion vulnerability in the Zephyr RTOS network stack. It occurs because the ICMP handlers for IPv4 and IPv6 are registered in a shared list, causing an IPv4 packet containing ICMP type 128 to be mistakenly processed by the ICMPv6 echo request handler. This misclassification leads to the IPv4 header being interpreted as an IPv6 header, resulting in an out-of-bounds memory read. This flaw can cause information leakage from the networking subsystem. [1]

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Impact Analysis

This vulnerability can lead to an out-of-bounds memory read in the Zephyr network stack, potentially leaking sensitive information from memory beyond intended boundaries. An attacker could exploit this by crafting specific IPv4 packets with ICMP type 128 to trigger the flaw, possibly causing unintended data disclosure. The impact includes confidentiality loss and a low availability impact due to the out-of-bounds read. [1]

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Detection Guidance

This vulnerability can be detected by monitoring network traffic for IPv4 packets containing ICMP type 128, which is normally an ICMPv6 Echo Request type but misclassified here. You can use packet capture tools like tcpdump or Wireshark to filter and analyze such packets. For example, using tcpdump: `tcpdump -n icmp and icmp[0] == 128` to capture IPv4 ICMP packets with type 128. Additionally, reviewing logs or debugging output from the Zephyr network stack for calls to the ICMPv6 echo request handler during IPv4 packet processing may help identify exploitation attempts. [1]

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Mitigation Strategies

Immediate mitigation steps include applying the available patches submitted for the Zephyr RTOS network stack, specifically the patches referenced as main: #98780, v4.2: #98983, v4.1: #98984, and v3.7: #98985. Until patches are applied, consider restricting or filtering incoming IPv4 ICMP packets with type 128 at network boundaries to reduce exposure. Monitoring network traffic for suspicious ICMP packets and limiting network access to trusted sources can also help mitigate risk. [1]

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Compliance Impact

The vulnerability could potentially lead to information leakage due to out-of-bounds memory reads in the Zephyr network stack. Such data leakage risks may impact compliance with data protection regulations like GDPR and HIPAA, which require safeguarding sensitive information against unauthorized disclosure. However, the provided resources do not explicitly discuss compliance implications or specific regulatory impacts. [1]

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