{"id":"CVE-2026-53003","title":"In the Linux kernel, the following vulnerability has been resolved:\n\npppoe: drop PFC frames\n\nRFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT\nRECOMMENDED for PPPoE","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\npppoe: drop PFC frames\n\nRFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT\nRECOMMENDED for PPPoE. In practice, pppd does not support negotiating\nPFC…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","published":"2026-06-24","updated":"2026-07-10","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-53003","references":[{"url":"https://git.kernel.org/stable/c/0cab5d077dd1efd2bd1a47271acc35894f945b4f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2b5c3c040d020e3ab3b9a8887031202d96843b1e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8a5e840babc5c0fbd10c73728a13192347771ec6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ba758fdf1399f310b30098b6faa3fd043de47dd2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cb3beef35ab5e0c1afca9fd7648c6ae499786377","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cc1ff87bce1ccd38410ab10960f576dcd17db679","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fcca1df05322bb04e344dd1178b54b76a08eb7c3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00501,"epssPercentile":0.41776,"ingestedAt":"2026-07-11T16:13:33.618Z","slug":"CVE-2026-53003","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\npppoe: drop PFC frames\n\nRFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT\nRECOMMENDED for PPPoE. In practice, pppd does not support negotiating\nPFC for PPPoE sessions, and the current PPPoE driver assumes an\nuncompressed (2-byte) protocol field. However, the generic PPP layer\nfunction ppp_input() is not aware of the negotiation result, and still\naccepts PFC frames.\n\nIf a peer with a broken implementation or an attacker sends a frame with\na compressed (1-byte) protocol field, the subsequent PPP payload is\nshifted by one byte. This causes the network header to be 4-byte\nmisaligned, which may trigger unaligned access exceptions on some\narchitectures.\n\nTo reduce the attack surface, drop PPPoE PFC frames. Introduce\nppp_skb_is_compressed_proto() helper function to be used in both\nppp_generic.c and pppoe.c to avoid open-coding.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}