{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23200", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.986Z", "datePublished": "2026-02-14T16:27:25.025Z", "dateUpdated": "2026-05-23T16:04:06.072Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-23T16:04:06.072Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF\n\nsyzbot reported a kernel BUG in fib6_add_rt2node() when adding an IPv6\nroute. [0]\n\nCommit f72514b3c569 (\"ipv6: clear RA flags when adding a static\nroute\") introduced logic to clear RTF_ADDRCONF from existing routes\nwhen a static route with the same nexthop is added. However, this\ncauses a problem when the existing route has a gateway.\n\nWhen RTF_ADDRCONF is cleared from a route that has a gateway, that\nroute becomes eligible for ECMP, i.e. rt6_qualify_for_ecmp() returns\ntrue. The issue is that this route was never added to the\nfib6_siblings list.\n\nThis leads to a mismatch between the following counts:\n\n- The sibling count computed by iterating fib6_next chain, which\n includes the newly ECMP-eligible route\n\n- The actual siblings in fib6_siblings list, which does not include\n that route\n\nWhen a subsequent ECMP route is added, fib6_add_rt2node() hits\nBUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings) because the\ncounts don't match.\n\nFix this by only clearing RTF_ADDRCONF when the existing route does\nnot have a gateway. Routes without a gateway cannot qualify for ECMP\nanyway (rt6_qualify_for_ecmp() requires fib_nh_gw_family), so clearing\nRTF_ADDRCONF on them is safe and matches the original intent of the\ncommit.\n\n[0]:\nkernel BUG at net/ipv6/ip6_fib.c:1217!\nOops: invalid opcode: 0000 [#1] SMP KASAN PTI\nCPU: 0 UID: 0 PID: 6010 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nRIP: 0010:fib6_add_rt2node+0x3433/0x3470 net/ipv6/ip6_fib.c:1217\n[...]\nCall Trace:\n \n fib6_add+0x8da/0x18a0 net/ipv6/ip6_fib.c:1532\n __ip6_ins_rt net/ipv6/route.c:1351 [inline]\n ip6_route_add+0xde/0x1b0 net/ipv6/route.c:3946\n ipv6_route_ioctl+0x35c/0x480 net/ipv6/route.c:4571\n inet6_ioctl+0x219/0x280 net/ipv6/af_inet6.c:577\n sock_do_ioctl+0xdc/0x300 net/socket.c:1245\n sock_ioctl+0x576/0x790 net/socket.c:1366\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:597 [inline]\n __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f" } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_fib.c" ], "versions": [ { "version": "cb2b0caa8ca93cbe39177516669bf699c74f7041", "lessThan": "50b7c7a255858a85c4636a1e990ca04591153dca", "status": "affected", "versionType": "git" }, { "version": "03f642caab84bbfd138e74f671bb436186ea7e82", "lessThan": "d8143c54ceeba232dc8a13aa0afa14a44b371d93", "status": "affected", "versionType": "git" }, { "version": "3e5b25da0b4109a3e063759735e6ec4236ea5a05", "lessThan": "b8ad2d53f706aeea833d23d45c0758398fede580", "status": "affected", "versionType": "git" }, { "version": "f72514b3c5698e4b900b25345e09f9ed33123de6", "lessThan": "bbf4a17ad9ffc4e3d7ec13d73ecd59dea149ed25", "status": "affected", "versionType": "git" }, { "version": "61d88ea0f30c88e4ea98793594943aed8f1fc9ab", "status": "affected", "versionType": "git" }, { "version": "6.17.13", "lessThan": "6.18", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_fib.c" ], "versions": [ { "version": "6.6.120", "lessThan": "6.6.124", "status": "affected", "versionType": "semver" }, { "version": "6.12.63", "lessThan": "6.12.70", "status": "affected", "versionType": "semver" }, { "version": "6.18.2", "lessThan": "6.18.10", "status": "affected", "versionType": "semver" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.120", "versionEndExcluding": "6.6.124" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.63", "versionEndExcluding": "6.12.70" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.2", "versionEndExcluding": "6.18.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.17.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/50b7c7a255858a85c4636a1e990ca04591153dca" }, { "url": "https://git.kernel.org/stable/c/d8143c54ceeba232dc8a13aa0afa14a44b371d93" }, { "url": "https://git.kernel.org/stable/c/b8ad2d53f706aeea833d23d45c0758398fede580" }, { "url": "https://git.kernel.org/stable/c/bbf4a17ad9ffc4e3d7ec13d73ecd59dea149ed25" } ], "title": "ipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF", "x_generator": { "engine": "bippy-1.2.0" } } } }