{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-56703", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T15:00:39.856Z", "datePublished": "2024-12-28T09:46:24.978Z", "dateUpdated": "2026-08-05T11:46:09.244Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:46:09.244Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix soft lockups in fib6_select_path under high next hop churn\n\nSoft lockups have been observed on a cluster of Linux-based edge routers\nlocated in a highly dynamic environment. Using the `bird` service, these\nrouters continuously update BGP-advertised routes due to frequently\nchanging nexthop destinations, while also managing significant IPv6\ntraffic. The lockups occur during the traversal of the multipath\ncircular linked-list in the `fib6_select_path` function, particularly\nwhile iterating through the siblings in the list. The issue typically\narises when the nodes of the linked list are unexpectedly deleted\nconcurrently on a different core—indicated by their 'next' and\n'previous' elements pointing back to the node itself and their reference\ncount dropping to zero. This results in an infinite loop, leading to a\nsoft lockup that triggers a system panic via the watchdog timer.\n\nApply RCU primitives in the problematic code sections to resolve the\nissue. Where necessary, update the references to fib6_siblings to\nannotate or use the RCU APIs.\n\nInclude a test script that reproduces the issue. The script\nperiodically updates the routing table while generating a heavy load\nof outgoing IPv6 traffic through multiple iperf3 clients. It\nconsistently induces infinite soft lockups within a couple of minutes.\n\nKernel log:\n\n 0 [ffffbd13003e8d30] machine_kexec at ffffffff8ceaf3eb\n 1 [ffffbd13003e8d90] __crash_kexec at ffffffff8d0120e3\n 2 [ffffbd13003e8e58] panic at ffffffff8cef65d4\n 3 [ffffbd13003e8ed8] watchdog_timer_fn at ffffffff8d05cb03\n 4 [ffffbd13003e8f08] __hrtimer_run_queues at ffffffff8cfec62f\n 5 [ffffbd13003e8f70] hrtimer_interrupt at ffffffff8cfed756\n 6 [ffffbd13003e8fd0] __sysvec_apic_timer_interrupt at ffffffff8cea01af\n 7 [ffffbd13003e8ff0] sysvec_apic_timer_interrupt at ffffffff8df1b83d\n-- --\n 8 [ffffbd13003d3708] asm_sysvec_apic_timer_interrupt at ffffffff8e000ecb\n [exception RIP: fib6_select_path+299]\n RIP: ffffffff8ddafe7b RSP: ffffbd13003d37b8 RFLAGS: 00000287\n RAX: ffff975850b43600 RBX: ffff975850b40200 RCX: 0000000000000000\n RDX: 000000003fffffff RSI: 0000000051d383e4 RDI: ffff975850b43618\n RBP: ffffbd13003d3800 R8: 0000000000000000 R9: ffff975850b40200\n R10: 0000000000000000 R11: 0000000000000000 R12: ffffbd13003d3830\n R13: ffff975850b436a8 R14: ffff975850b43600 R15: 0000000000000007\n ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018\n 9 [ffffbd13003d3808] ip6_pol_route at ffffffff8ddb030c\n10 [ffffbd13003d3888] ip6_pol_route_input at ffffffff8ddb068c\n11 [ffffbd13003d3898] fib6_rule_lookup at ffffffff8ddf02b5\n12 [ffffbd13003d3928] ip6_route_input at ffffffff8ddb0f47\n13 [ffffbd13003d3a18] ip6_rcv_finish_core.constprop.0 at ffffffff8dd950d0\n14 [ffffbd13003d3a30] ip6_list_rcv_finish.constprop.0 at ffffffff8dd96274\n15 [ffffbd13003d3a98] ip6_sublist_rcv at ffffffff8dd96474\n16 [ffffbd13003d3af8] ipv6_list_rcv at ffffffff8dd96615\n17 [ffffbd13003d3b60] __netif_receive_skb_list_core at ffffffff8dc16fec\n18 [ffffbd13003d3be0] netif_receive_skb_list_internal at ffffffff8dc176b3\n19 [ffffbd13003d3c50] napi_gro_receive at ffffffff8dc565b9\n20 [ffffbd13003d3c80] ice_receive_skb at ffffffffc087e4f5 [ice]\n21 [ffffbd13003d3c90] ice_clean_rx_irq at ffffffffc0881b80 [ice]\n22 [ffffbd13003d3d20] ice_napi_poll at ffffffffc088232f [ice]\n23 [ffffbd13003d3d80] __napi_poll at ffffffff8dc18000\n24 [ffffbd13003d3db8] net_rx_action at ffffffff8dc18581\n25 [ffffbd13003d3e40] __do_softirq at ffffffff8df352e9\n26 [ffffbd13003d3eb0] run_ksoftirqd at ffffffff8ceffe47\n27 [ffffbd13003d3ec0] smpboot_thread_fn at ffffffff8cf36a30\n28 [ffffbd13003d3ee8] kthread at ffffffff8cf2b39f\n29 [ffffbd13003d3f28] ret_from_fork at ffffffff8ce5fa64\n30 [ffffbd13003d3f50] ret_from_fork_asm at ffffffff8ce03cbb" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable traversal runs in the IPv6 packet receive/forwarding path (`ip6_route_input` → `ip6_pol_route` → `fib6_select_path`) in NAPI softirq context, as shown by the crash trace, so remote IPv6 packets arriving over the network drive the loop. The reported real-world failures were edge routers panicking while forwarding remote traffic.\nAC:L - The attacker fully controls the packet-lookup side of the race and can flood the target at will, and in the vulnerable configuration (multipath ECMP routes with BGP-driven nexthop churn) the deletion side occurs continuously, so the reproducer reliably wedges a CPU within a couple of minutes; a local attacker with a user namespace controls both sides outright.\nPR:N - No authentication or privilege is needed to send IPv6 traffic that the router looks up in the multipath FIB — the route lookup happens before any socket, credential, or filtering decision. The privileged half of the race is performed by the victim's own routing daemon.\nUI:N - The loop is entered purely by kernel packet processing; no action by any local user or administrator is required beyond the routing daemon's normal operation.\nS:U - The impact is confined to the kernel of the affected host — a wedged CPU and panic — with no crossing into a different security authority such as a hypervisor or IOMMU boundary.\nC:N - The traversal repeatedly re-reads a valid, RCU-protected `fib6_info` object; no out-of-bounds or freed memory is read and no data is returned to the attacker.\nI:N - There is no memory corruption or out-of-bounds write — the fix only adds RCU list annotations — so no kernel or user data can be modified.\nA:H - The self-referential list node causes an unbreakable infinite loop in softirq context, permanently consuming a CPU, stalling RCU and network processing, and triggering a watchdog soft lockup that panics the machine, as observed on production routers." } ] } ], "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", "net/ipv6/route.c", "tools/testing/selftests/net/Makefile", "tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh" ], "versions": [ { "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83", "lessThan": "d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2", "status": "affected", "versionType": "git" }, { "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83", "lessThan": "52da02521ede55fb86546c3fffd9377b3261b91f", "status": "affected", "versionType": "git" }, { "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83", "lessThan": "11edcd026012ac18acee0f1514db3ed1b160fc6f", "status": "affected", "versionType": "git" }, { "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83", "lessThan": "34a949e7a0869dfa31a40416d2a56973fae1807b", "status": "affected", "versionType": "git" }, { "version": "66f5d6ce53e665477d2a33e8f539d4fa4ca81c83", "lessThan": "d9ccb18f83ea2bb654289b6ecf014fd267cc988b", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_fib.c", "net/ipv6/route.c", "tools/testing/selftests/net/Makefile", "tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh" ], "versions": [ { "version": "4.15", "status": "affected" }, { "version": "0", "lessThan": "4.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.128", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.75", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.11", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.2", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.1.128" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.6.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.11.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.12.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2" }, { "url": "https://git.kernel.org/stable/c/52da02521ede55fb86546c3fffd9377b3261b91f" }, { "url": "https://git.kernel.org/stable/c/11edcd026012ac18acee0f1514db3ed1b160fc6f" }, { "url": "https://git.kernel.org/stable/c/34a949e7a0869dfa31a40416d2a56973fae1807b" }, { "url": "https://git.kernel.org/stable/c/d9ccb18f83ea2bb654289b6ecf014fd267cc988b" } ], "title": "ipv6: Fix soft lockups in fib6_select_path under high next hop churn", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2024-56703", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2025-10-01T19:58:51.187430Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-835", "description": "CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T20:07:07.422Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:52:52.353Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:38:39.047Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }