The Linux kernel PPPoE driver mistakenly accepts a single‑byte compressed protocol field when the generic PPP input routine expects a two‑byte field. This causes a 1‑byte shift in the payload, misaligning the network header and triggering unaligned memory accesses on architectures that enforce strict alignment. The flaw is a form of incorrect data‑structure handling, identified by CWE-1102 and CWE-20, and the NVD entry was noted as having no specific CWE mapping.

All Linux kernel installations that include PPPoE support and have not applied the patch that drops PFC frames are potentially affected. The CPE indicates any Linux kernel, and no specific version range is provided, implying that older kernels prior to the patch carry the issue. Based on the nature of PPPoE usage, it is inferred that devices such as routers, DSL modems, or VPN gateways are the most directly impacted.

The CVSS score of 7.5 indicates a higher severity vulnerability, and the EPSS score of less than 1% suggests a low likelihood of exploitation. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires an attacker able to inject specially crafted PPPoE packets against a vulnerable device. Based on the description, it is inferred that an attacker could target a vulnerable device on a shared LAN or WAN segment. The patch mitigates the issue by explicitly dropping PPPoE PFC frames, eliminating the opportunity for misaligned access and the resulting denial of service.