{"id":"CVE-2026-52942","title":"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-…","summary":"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-…","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","cwe":["CWE-125"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.36, < 5.15.210","linux_kernel >= 5.16, < 6.1.176","linux_kernel >= 6.2, < 6.6.143","linux_kernel >= 6.7, < 6.12.94","linux_kernel >= 6.13, < 6.18.36","linux_kernel >= 6.19, < 7.0.13","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.13"],"published":"2026-06-24","updated":"2026-09-08","sourceUpdated":"2026-09-08T09:18:11.710","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-52942","references":[{"url":"https://git.kernel.org/stable/c/2e96e1bc9b4d5450e6c33f078e19a9bc1dda6c0b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/65ef7397eb9a296e91839f5fd10be96f23d332e7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8a81e336da685423f5b64aac4d571e63d674c52a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a84b6fedbc97078788be78dbdd7517d143ad1a77","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/af1b7699466f6556b351fa25d3dc870abfb5d310","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/befb8968a2abdfa948d5600ea7f7a509a292a590","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c38d41134085193efd5b237cf513ad5b3421a60d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d704ee9c7bc68a161684c51a7ac05b446dcf38d4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52942.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-52942"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2492091"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-52942"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52942"},{"url":"https://lore.kernel.org/linux-cve-announce/2026062435-CVE-2026-52942-2530@gregkh/T"},{"url":"https://access.redhat.com/errata/RHSA-2026:66325"},{"url":"https://access.redhat.com/errata/RHSA-2026:66324"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00128,"epssPercentile":0.02034,"ingestedAt":"2026-09-08T13:33:25.159Z","scores":{"nvd":7.1,"vendor":7},"slug":"CVE-2026-52942","body":"## Overview\n\nIn 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)\n\n## Affected\n\n- `linux_kernel >= 2.6.36, < 5.15.210`\n- `linux_kernel >= 5.16, < 6.1.176`\n- `linux_kernel >= 6.2, < 6.6.143`\n- `linux_kernel >= 6.7, < 6.12.94`\n- `linux_kernel >= 6.13, < 6.18.36`\n- `linux_kernel >= 6.19, < 7.0.13`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.13`\n\n## Vendor advisories\n\n- **RHSA-2026:66325** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66325)\n- **RHSA-2026:66324** · Red Hat · fixed in: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66324)\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-09-10 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52942.json)","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}