{"id":"CVE-2026-53003","summary":"pppoe: drop PFC frames","details":"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 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.","modified":"2026-07-22T18:22:29.443732404Z","published":"2026-06-24T16:29:15.268Z","related":["SUSE-SU-2026:3130-1","SUSE-SU-2026:3166-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53003.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0cab5d077dd1efd2bd1a47271acc35894f945b4f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2b5c3c040d020e3ab3b9a8887031202d96843b1e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8a5e840babc5c0fbd10c73728a13192347771ec6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ba758fdf1399f310b30098b6faa3fd043de47dd2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb3beef35ab5e0c1afca9fd7648c6ae499786377"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cc1ff87bce1ccd38410ab10960f576dcd17db679"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fcca1df05322bb04e344dd1178b54b76a08eb7c3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53003.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53003"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7fb1b8ca8fa1ee34ffc328f17f78da68c7cc04e6"},{"fixed":"cb3beef35ab5e0c1afca9fd7648c6ae499786377"},{"fixed":"ba758fdf1399f310b30098b6faa3fd043de47dd2"},{"fixed":"fcca1df05322bb04e344dd1178b54b76a08eb7c3"},{"fixed":"8a5e840babc5c0fbd10c73728a13192347771ec6"},{"fixed":"49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71"},{"fixed":"0cab5d077dd1efd2bd1a47271acc35894f945b4f"},{"fixed":"2b5c3c040d020e3ab3b9a8887031202d96843b1e"},{"fixed":"cc1ff87bce1ccd38410ab10960f576dcd17db679"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-53003.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.10.258"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.209"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.175"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.141"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.91"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.33"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-53003.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}