{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63968", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.024Z", "datePublished": "2026-07-19T14:55:55.620Z", "dateUpdated": "2026-08-05T12:37:40.633Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:40.633Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix possible infinite loop in fib6_select_path()\n\nFound while auditing the same pattern Sashiko reported in\nrt6_fill_node() [1]. Apply the same fix as\ncommit f8d8ce1b515a (\"ipv6: fix possible infinite loop in fib6_info_uses_dev()\").\n\nWriters holding tb6_lock can list_del_rcu(&first->fib6_siblings)\nwithout waiting for RCU readers; first->fib6_siblings.next then\nstill points into the old ring and this softirq-side walker never\nreaches &first->fib6_siblings as its terminator. fib6_purge_rt()\nalways WRITE_ONCE()s first->fib6_nsiblings to 0 before\nlist_del_rcu(), so an inside-loop check is a reliable detach signal.\n\n[1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev" } ], "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 function is reached from the IPv6 packet receive path (ipv6_rcv → ip6_route_input → ip6_pol_route → fib6_select_path) in softirq context, and production lockups were observed during processing of incoming IPv6 traffic on internet-facing edge routers.\nAC:L - The race is reliably triggerable when an attacker influences both packet flow and route churn (e.g., user-namespace ECMP setup plus traffic, or remote traffic coinciding with BGP nexthop updates); a dedicated selftest reproduces soft lockups in under a minute under controlled conditions.\nPR:N - Triggering fib6_select_path() during packet processing requires only the ability to send IPv6 traffic to destinations using multipath routes; concurrent route-table updates can occur from infrastructure (BGP/dynamic routing) without the attacker holding any local privileges.\nUI:N - Exploitation requires no victim interaction beyond normal network traffic delivery to a host or router processing IPv6 packets.\nS:U - The impact is kernel CPU soft lockup and watchdog panic within the same kernel security boundary; there is no sandbox, VM, or IOMMU boundary crossing.\nC:N - The bug is an infinite loop over stale sibling-list pointers during RCU read-side traversal; it does not read or disclose attacker-controlled memory or kernel secrets.\nI:N - No data modification or memory corruption occurs; the failure mode is CPU hang from unbounded list iteration, not arbitrary write or code execution.\nA:H - The infinite loop in softirq context causes CPU soft lockup, and documented production and test cases show this leads to watchdog-triggered kernel panic, a complete loss of system availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/route.c" ], "versions": [ { "version": "d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2", "lessThan": "3948a7d92f7678e89e1776bb2d169afcad63b1ae", "status": "affected", "versionType": "git" }, { "version": "52da02521ede55fb86546c3fffd9377b3261b91f", "lessThan": "c87cd3cb309634bc8f50a54e2079424f219ac21f", "status": "affected", "versionType": "git" }, { "version": "34a949e7a0869dfa31a40416d2a56973fae1807b", "lessThan": "0f7b73c3452635de83b8711b31abdda8e49aad7b", "status": "affected", "versionType": "git" }, { "version": "d9ccb18f83ea2bb654289b6ecf014fd267cc988b", "lessThan": "ab9a10969a907b472a0196d999c08ff7144172e3", "status": "affected", "versionType": "git" }, { "version": "d9ccb18f83ea2bb654289b6ecf014fd267cc988b", "lessThan": "9b9d5bd6e3d4c9cecab5407604b690684b2532d2", "status": "affected", "versionType": "git" }, { "version": "d9ccb18f83ea2bb654289b6ecf014fd267cc988b", "lessThan": "9c7da87c2dc860bb17ca1ece942495d28b1ce3b9", "status": "affected", "versionType": "git" }, { "version": "11edcd026012ac18acee0f1514db3ed1b160fc6f", "status": "affected", "versionType": "git" }, { "version": "6.1.128", "lessThan": "6.1.176", "status": "affected", "versionType": "semver" }, { "version": "6.6.75", "lessThan": "6.6.143", "status": "affected", "versionType": "semver" }, { "version": "6.12.2", "lessThan": "6.12.93", "status": "affected", "versionType": "semver" }, { "version": "6.11.11", "lessThan": "6.12", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/route.c" ], "versions": [ { "version": "6.13", "status": "affected" }, { "version": "0", "lessThan": "6.13", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.1.128", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.75", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.2", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.11.11" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3948a7d92f7678e89e1776bb2d169afcad63b1ae" }, { "url": "https://git.kernel.org/stable/c/c87cd3cb309634bc8f50a54e2079424f219ac21f" }, { "url": "https://git.kernel.org/stable/c/0f7b73c3452635de83b8711b31abdda8e49aad7b" }, { "url": "https://git.kernel.org/stable/c/ab9a10969a907b472a0196d999c08ff7144172e3" }, { "url": "https://git.kernel.org/stable/c/9b9d5bd6e3d4c9cecab5407604b690684b2532d2" }, { "url": "https://git.kernel.org/stable/c/9c7da87c2dc860bb17ca1ece942495d28b1ce3b9" } ], "title": "ipv6: fix possible infinite loop in fib6_select_path()", "x_generator": { "engine": "bippy-1.2.0" } } } }