{"id":"CVE-2026-23304","state":"PUBLISHED","title":"ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()\n\nl3mdev_master_dev_rcu() can return NULL when the slave device is being\nun-slaved from a VRF. All other callers deal with this, but we lost\nthe fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu()\nwith commit 4832c30d5458 (\"net: ipv6: put host and anycast routes on\ndevice with address\").\n\n  KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]\n  RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418)\n  Call Trace:\n   ip6_pol_route (net/ipv6/route.c:2318)\n   fib6_rule_lookup (net/ipv6/fib6_rules.c:115)\n   ip6_route_output_flags (net/ipv6/route.c:2607)\n   vrf_process_v6_outbound (drivers/net/vrf.c:437)\n\nI was tempted to rework the un-slaving code to clear the flag first\nand insert synchronize_rcu() before we remove the upper. But looks like\nthe explicit fallback to loopback_dev is an established pattern.\nAnd I guess avoiding the synchronize_rcu() is nice, too.","publishedAt":"2026-03-25T10:26:59.015Z","updatedAt":"2026-10-15T01:13:54.349Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"d542e2ac7f9e288d49735be0775611547ca4e0ee","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"a73fe9f4ae84a239d5b2686f47a58c158aee2eb4","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"4a48fe59f29f673a3d042d679f26629a9c3e29d4","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"581800298313c9fd75e94985e6d37d21b7e35d34","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"3310fc11fc47387d1dd4759b0bc961643ea11c7f","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"0b5a7826020706057cc5a9d9009e667027f221ee","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"ae88c8256547b63980770a9ea7be73a15900d27e","versionType":"git"},{"version":"4832c30d5458387ff2533ff66fbde26ad8bb5a2d","status":"affected","lessThan":"2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.14","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.77","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]}],"references":["https://git.kernel.org/stable/c/d542e2ac7f9e288d49735be0775611547ca4e0ee","https://git.kernel.org/stable/c/a73fe9f4ae84a239d5b2686f47a58c158aee2eb4","https://git.kernel.org/stable/c/4a48fe59f29f673a3d042d679f26629a9c3e29d4","https://git.kernel.org/stable/c/581800298313c9fd75e94985e6d37d21b7e35d34","https://git.kernel.org/stable/c/3310fc11fc47387d1dd4759b0bc961643ea11c7f","https://git.kernel.org/stable/c/0b5a7826020706057cc5a9d9009e667027f221ee","https://git.kernel.org/stable/c/ae88c8256547b63980770a9ea7be73a15900d27e","https://git.kernel.org/stable/c/2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23304.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23304","state":"PUBLISHED","datePublished":"2026-03-25T10:26:59.015Z","dateUpdated":"2026-10-15T01:13:54.349Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:45.993Z"},"containers":{"cna":{"title":"ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()\n\nl3mdev_master_dev_rcu() can return NULL when the slave device is being\nun-slaved from a VRF. All other callers deal with this, but we lost\nthe fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu()\nwith commit 4832c30d5458 (\"net: ipv6: put host and anycast routes on\ndevice with address\").\n\n  KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]\n  RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418)\n  Call Trace:\n   ip6_pol_route (net/ipv6/route.c:2318)\n   fib6_rule_lookup (net/ipv6/fib6_rules.c:115)\n   ip6_route_output_flags (net/ipv6/route.c:2607)\n   vrf_process_v6_outbound (drivers/net/vrf.c:437)\n\nI was tempted to rework the un-slaving code to clear the flag first\nand insert synchronize_rcu() before we remove the upper. 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