{"id":"CVE-2026-23124","title":"ipv6: annotate data-race in ndisc_router_discovery()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: annotate data-race in ndisc_router_discovery()\n\nsyzbot found that ndisc_router_discovery() could read and write\nin6_dev->ra_mtu without holding a lock [1]\n\nThis l…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 4630897eb1a039b5d7b737b8dc9521d9d4b568b5","Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 2619499169fb1c2ac4974b0f2d87767fb543582b","Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < fad8f4ff7928f4d52a062ffdcffa484989c79c47","Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 2a2b9d25f801afecf2f83cacce98afa8fd73e3c9","Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < e3c1040252e598f7b4e33a42dc7c38519bc22428","Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 9a063f96d87efc3a6cc667f8de096a3d38d74bb5","Linux 5.15"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-06-10T20:40:30.553217Z"},"published":"2026-02-14","updated":"2026-10-19","sourceUpdated":"2026-10-19T18:25:32.245Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23124","references":[{"url":"https://git.kernel.org/stable/c/4630897eb1a039b5d7b737b8dc9521d9d4b568b5"},{"url":"https://git.kernel.org/stable/c/2619499169fb1c2ac4974b0f2d87767fb543582b"},{"url":"https://git.kernel.org/stable/c/fad8f4ff7928f4d52a062ffdcffa484989c79c47"},{"url":"https://git.kernel.org/stable/c/2a2b9d25f801afecf2f83cacce98afa8fd73e3c9"},{"url":"https://git.kernel.org/stable/c/e3c1040252e598f7b4e33a42dc7c38519bc22428"},{"url":"https://git.kernel.org/stable/c/9a063f96d87efc3a6cc667f8de096a3d38d74bb5"}],"tags":["cve.org"],"epss":0.00134,"epssPercentile":0.02572,"ingestedAt":"2026-10-19T18:35:50.102Z","slug":"CVE-2026-23124","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nipv6: annotate data-race in ndisc_router_discovery()\n\nsyzbot found that ndisc_router_discovery() could read and write\nin6_dev->ra_mtu without holding a lock [1]\n\nThis looks fine, IFLA_INET6_RA_MTU is best effort.\n\nAdd READ_ONCE()/WRITE_ONCE() to document the race.\n\nNote that we might also reject illegal MTU values\n(mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) in a future patch.\n\n[1]\nBUG: KCSAN: data-race in ndisc_router_discovery / ndisc_router_discovery\n\nread to 0xffff888119809c20 of 4 bytes by task 25817 on cpu 1:\n  ndisc_router_discovery+0x151d/0x1c90 net/ipv6/ndisc.c:1558\n  ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841\n  icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989\n  ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438\n  ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489\n  NF_HOOK include/linux/netfilter.h:318 [inline]\n  ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500\n  ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590\n  dst_input include/net/dst.h:474 [inline]\n  ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79\n...\n\nwrite to 0xffff888119809c20 of 4 bytes by task 25816 on cpu 0:\n  ndisc_router_discovery+0x155a/0x1c90 net/ipv6/ndisc.c:1559\n  ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841\n  icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989\n  ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438\n  ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489\n  NF_HOOK include/linux/netfilter.h:318 [inline]\n  ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500\n  ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590\n  dst_input include/net/dst.h:474 [inline]\n  ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79\n...\n\nvalue changed: 0x00000000 -> 0xe5400659\n\n## Affected\n\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 4630897eb1a039b5d7b737b8dc9521d9d4b568b5`\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 2619499169fb1c2ac4974b0f2d87767fb543582b`\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < fad8f4ff7928f4d52a062ffdcffa484989c79c47`\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 2a2b9d25f801afecf2f83cacce98afa8fd73e3c9`\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < e3c1040252e598f7b4e33a42dc7c38519bc22428`\n- `Linux >= 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 < 9a063f96d87efc3a6cc667f8de096a3d38d74bb5`\n- `Linux 5.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}