{"id":"CVE-2026-52942","revision":"2346c006259f4df092c0c2920467a81e","records":[{"revision":"2346c006259f4df092c0c2920467a81e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-52942","aliases":[],"title":"netfilter: nf_log: validate MAC header was set before dumping it","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_log: validate MAC header was set before dumping it\n\nThe fallback path of dump_mac_header() guards the MAC header access\nonly with \"skb->mac_header != skb->network_header\", without checking\nskb_mac_header_was_set(). When the MAC header is unset, mac_header is\n0xffff, so the test passes and skb_mac_header(skb) returns\nskb->head + 0xffff, ~64 KiB past the buffer; the loop then reads\ndev->hard_header_len bytes out of bounds into the kernel log.\n\nThis is reachable via the netdev logger: nf_log_unknown_packet() calls\ndump_mac_header() unconditionally, and an skb sent through AF_PACKET\nwith PACKET_QDISC_BYPASS reaches the egress hook with mac_header still\nunset (__dev_queue_xmit(), which would reset it, is bypassed).\n\nAdd the skb_mac_header_was_set() check the ARPHRD_ETHER path already\nuses, and replace the open-coded MAC header length test with\nskb_mac_header_len(). Only skbs with an unset MAC header are affected;\nvalid ones are dumped as before.\n\n BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n Read of size 1 at addr ffff88800ea49d3f by task exploit/148\n Call Trace:\n  kasan_report (mm/kasan/report.c:595)\n  dump_mac_header (net/netfilter/nf_log_syslog.c:831)\n  nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963)\n  nf_log_packet (net/netfilter/nf_log.c:260)\n  nft_log_eval (net/netfilter/nft_log.c:60)\n  nft_do_chain (net/netfilter/nf_tables_core.c:285)\n  nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307)\n  nf_hook_slow (net/netfilter/core.c:619)\n  nf_hook_direct_egress (net/packet/af_packet.c:257)\n  packet_xmit (net/packet/af_packet.c:280)\n  packet_sendmsg (net/packet/af_packet.c:3114)\n  __sys_sendto (net/socket.c:2265)","state":0,"publishedAt":"2026-06-24T07:14:30.61+00:00","modifiedAt":"2026-10-19T19:47:08.584+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/netfilter/nf_log_syslog.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"2e96e1bc9b4d5450e6c33f078e19a9bc1dda6c0b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"d704ee9c7bc68a161684c51a7ac05b446dcf38d4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"befb8968a2abdfa948d5600ea7f7a509a292a590\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"8a81e336da685423f5b64aac4d571e63d674c52a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"c38d41134085193efd5b237cf513ad5b3421a60d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"af1b7699466f6556b351fa25d3dc870abfb5d310\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"65ef7397eb9a296e91839f5fd10be96f23d332e7\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"7eb9282cd0efac08b8377cbd5037ba297c77e3f7\",\n                            \"lessThan\": \"a84b6fedbc97078788be78dbdd7517d143ad1a77\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/netfilter/nf_log_syslog.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"2.6.36\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"2.6.36\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.261\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.210\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.176\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.143\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.94\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.36\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.13\",\n                            \"lessThanOrEqual\": \"7.0.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","score":7.1,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/2e96e1bc9b4d5450e6c33f078e19a9bc1dda6c0b","https://git.kernel.org/stable/c/d704ee9c7bc68a161684c51a7ac05b446dcf38d4","https://git.kernel.org/stable/c/befb8968a2abdfa948d5600ea7f7a509a292a590","https://git.kernel.org/stable/c/8a81e336da685423f5b64aac4d571e63d674c52a","https://git.kernel.org/stable/c/c38d41134085193efd5b237cf513ad5b3421a60d","https://git.kernel.org/stable/c/af1b7699466f6556b351fa25d3dc870abfb5d310","https://git.kernel.org/stable/c/65ef7397eb9a296e91839f5fd10be96f23d332e7","https://git.kernel.org/stable/c/a84b6fedbc97078788be78dbdd7517d143ad1a77"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-52942","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-52942","identifiers":["CVE-2026-52942"]},"retained":false,"historicalAffected":[]}],"coverage":[]}