{"id":"CVE-2025-21891","summary":"ipvlan: ensure network headers are in skb linear part","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipvlan: ensure network headers are in skb linear part\n\nsyzbot found that ipvlan_process_v6_outbound() was assuming\nthe IPv6 network header isis present in skb-\u003ehead [1]\n\nAdd the needed pskb_network_may_pull() calls for both\nIPv4 and IPv6 handlers.\n\n[1]\nBUG: KMSAN: uninit-value in __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47\n  __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47\n  ipv6_addr_type include/net/ipv6.h:555 [inline]\n  ip6_route_output_flags_noref net/ipv6/route.c:2616 [inline]\n  ip6_route_output_flags+0x51/0x720 net/ipv6/route.c:2651\n  ip6_route_output include/net/ip6_route.h:93 [inline]\n  ipvlan_route_v6_outbound+0x24e/0x520 drivers/net/ipvlan/ipvlan_core.c:476\n  ipvlan_process_v6_outbound drivers/net/ipvlan/ipvlan_core.c:491 [inline]\n  ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:541 [inline]\n  ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:605 [inline]\n  ipvlan_queue_xmit+0xd72/0x1780 drivers/net/ipvlan/ipvlan_core.c:671\n  ipvlan_start_xmit+0x5b/0x210 drivers/net/ipvlan/ipvlan_main.c:223\n  __netdev_start_xmit include/linux/netdevice.h:5150 [inline]\n  netdev_start_xmit include/linux/netdevice.h:5159 [inline]\n  xmit_one net/core/dev.c:3735 [inline]\n  dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3751\n  sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343\n  qdisc_restart net/sched/sch_generic.c:408 [inline]\n  __qdisc_run+0x14da/0x35d0 net/sched/sch_generic.c:416\n  qdisc_run+0x141/0x4d0 include/net/pkt_sched.h:127\n  net_tx_action+0x78b/0x940 net/core/dev.c:5484\n  handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561\n  __do_softirq+0x14/0x1a kernel/softirq.c:595\n  do_softirq+0x9a/0x100 kernel/softirq.c:462\n  __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:389\n  local_bh_enable include/linux/bottom_half.h:33 [inline]\n  rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]\n  __dev_queue_xmit+0x2758/0x57d0 net/core/dev.c:4611\n  dev_queue_xmit include/linux/netdevice.h:3311 [inline]\n  packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276\n  packet_snd net/packet/af_packet.c:3132 [inline]\n  packet_sendmsg+0x93e0/0xa7e0 net/packet/af_packet.c:3164\n  sock_sendmsg_nosec net/socket.c:718 [inline]","modified":"2026-04-02T12:45:16.230534Z","published":"2025-03-27T14:57:17.267Z","related":["SUSE-SU-2025:01919-1","SUSE-SU-2025:01951-1","SUSE-SU-2025:01967-1","SUSE-SU-2025:1177-1","SUSE-SU-2025:1178-1","SUSE-SU-2025:1180-1","SUSE-SU-2025:1293-1","SUSE-SU-2025:20190-1","SUSE-SU-2025:20192-1","SUSE-SU-2025:20260-1","SUSE-SU-2025:20270-1","USN-7521-2"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21891.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/27843ce6ba3d3122b65066550fe33fb8839f8aef"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4ec48f812804f370f622e0874e6dd8fcc58241cd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5353fd89663c48f56bdff975c562cfe78b1a2e4c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5b8dea8d1612dc7151d2457d7d2e6a69820309bf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e2a4f76a2d8a44816ecd25bcbdb47b786d621974"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21891.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21891"},{"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":"2ad7bf3638411cb547f2823df08166c13ab04269"},{"fixed":"5b8dea8d1612dc7151d2457d7d2e6a69820309bf"},{"fixed":"4ec48f812804f370f622e0874e6dd8fcc58241cd"},{"fixed":"5353fd89663c48f56bdff975c562cfe78b1a2e4c"},{"fixed":"e2a4f76a2d8a44816ecd25bcbdb47b786d621974"},{"fixed":"27843ce6ba3d3122b65066550fe33fb8839f8aef"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21891.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}