{"id":"CVE-2026-23124","state":"PUBLISHED","title":"ipv6: annotate data-race in ndisc_router_discovery()","description":"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 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","publishedAt":"2026-02-14T15:09:54.043Z","updatedAt":"2026-10-19T18:25:32.245Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"4630897eb1a039b5d7b737b8dc9521d9d4b568b5","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"2619499169fb1c2ac4974b0f2d87767fb543582b","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"fad8f4ff7928f4d52a062ffdcffa484989c79c47","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"2a2b9d25f801afecf2f83cacce98afa8fd73e3c9","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"e3c1040252e598f7b4e33a42dc7c38519bc22428","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"9a063f96d87efc3a6cc667f8de096a3d38d74bb5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ndisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.199","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.162","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.122","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.68","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.8","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ndisc.c"]}],"references":["https://git.kernel.org/stable/c/4630897eb1a039b5d7b737b8dc9521d9d4b568b5","https://git.kernel.org/stable/c/2619499169fb1c2ac4974b0f2d87767fb543582b","https://git.kernel.org/stable/c/fad8f4ff7928f4d52a062ffdcffa484989c79c47","https://git.kernel.org/stable/c/2a2b9d25f801afecf2f83cacce98afa8fd73e3c9","https://git.kernel.org/stable/c/e3c1040252e598f7b4e33a42dc7c38519bc22428","https://git.kernel.org/stable/c/9a063f96d87efc3a6cc667f8de096a3d38d74bb5"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23124.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23124","state":"PUBLISHED","datePublished":"2026-02-14T15:09:54.043Z","dateUpdated":"2026-10-19T18:25:32.245Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:45.970Z"},"containers":{"cna":{"title":"ipv6: annotate data-race in ndisc_router_discovery()","descriptions":[{"lang":"en","value":"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 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"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"4630897eb1a039b5d7b737b8dc9521d9d4b568b5","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"2619499169fb1c2ac4974b0f2d87767fb543582b","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"fad8f4ff7928f4d52a062ffdcffa484989c79c47","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"2a2b9d25f801afecf2f83cacce98afa8fd73e3c9","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"e3c1040252e598f7b4e33a42dc7c38519bc22428","versionType":"git"},{"version":"49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7","status":"affected","lessThan":"9a063f96d87efc3a6cc667f8de096a3d38d74bb5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ndisc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.199","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.162","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.122","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.68","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.8","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ndisc.c"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:00:35.572Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"5.15.199"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.1.162"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.122"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.68"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.19"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-23124","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-06-10T20:40:30.553217Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T18:25:32.245Z"}}]}}}