{"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"}}}}