{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-46099","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-05-13T15:03:33.097Z","datePublished":"2026-05-27T12:59:04.628Z","dateUpdated":"2026-06-30T12:10:13.161Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-06-14T17:54:21.059Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels\n\nseg6_input_core() and rpl_input() call ip6_route_input() which sets a\nNOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking\ndst_hold() unconditionally.\nOn PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can\nrelease the underlying pcpu_rt between the lookup and the caching\nthrough a concurrent FIB lookup on a shared nexthop.\nSimplified race sequence:\n\n  ksoftirqd/X                       higher-prio task (same CPU X)\n  -----------                       --------------------------------\n  seg6_input_core(,skb)/rpl_input(skb)\n    dst_cache_get()\n      -> miss\n    ip6_route_input(skb)\n      -> ip6_pol_route(,skb,flags)\n         [RT6_LOOKUP_F_DST_NOREF in flags]\n        -> FIB lookup resolves fib6_nh\n           [nhid=N route]\n        -> rt6_make_pcpu_route()\n           [creates pcpu_rt, refcount=1]\n             pcpu_rt->sernum = fib6_sernum\n             [fib6_sernum=W]\n           -> cmpxchg(fib6_nh.rt6i_pcpu,\n                      NULL, pcpu_rt)\n              [slot was empty, store succeeds]\n      -> skb_dst_set_noref(skb, dst)\n         [dst is pcpu_rt, refcount still 1]\n\n                                    rt_genid_bump_ipv6()\n                                      -> bumps fib6_sernum\n                                         [fib6_sernum from W to Z]\n                                    ip6_route_output()\n                                      -> ip6_pol_route()\n                                        -> FIB lookup resolves fib6_nh\n                                           [nhid=N]\n                                        -> rt6_get_pcpu_route()\n                                             pcpu_rt->sernum != fib6_sernum\n                                             [W <> Z, stale]\n                                          -> prev = xchg(rt6i_pcpu, NULL)\n                                          -> dst_release(prev)\n                                             [prev is pcpu_rt,\n                                              refcount 1->0, dead]\n\n    dst = skb_dst(skb)\n    [dst is the dead pcpu_rt]\n    dst_cache_set_ip6(dst)\n      -> dst_hold() on dead dst\n      -> WARN / use-after-free\n\nFor the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without\nPREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release\nthe pcpu_rt. Shared nexthop objects provide such a path, as two routes\npointing to the same nhid share the same fib6_nh and its rt6i_pcpu\nentry.\n\nFix seg6_input_core() and rpl_input() by calling skb_dst_force() after\nip6_route_input() to force the NOREF dst into a refcounted one before\ncaching.\nThe output path is not affected as ip6_route_output() already returns a\nrefcounted dst."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.1,"baseSeverity":"HIGH"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/rpl_iptunnel.c","net/ipv6/seg6_iptunnel.c"],"versions":[{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"51fef5a7c4d160839199e941929456ba21ddf73c","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"b258b849a580285a1692e782ebc902b44c884a71","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"6bd17925bd6866027a6555db17905b9fc073d38d","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"52f9db67f8f35f436366cf4980b4f0a2583d0ef0","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"b778b6d095421619c331fd2d7751143cd5387103","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"9dd5481f960e337b81d7dfe429529495c1c481c0","status":"affected","versionType":"git"},{"version":"af4a2209b1344939eaac11f269c261d347cbc3ee","lessThan":"f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e","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/rpl_iptunnel.c","net/ipv6/seg6_iptunnel.c"],"versions":[{"version":"4.12","status":"affected"},{"version":"0","lessThan":"4.12","status":"unaffected","versionType":"semver"},{"version":"5.15.209","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.175","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.140","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.86","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.27","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.4","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":"4.12","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.6.140"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.12.86"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.18.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.0.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/51fef5a7c4d160839199e941929456ba21ddf73c"},{"url":"https://git.kernel.org/stable/c/b258b849a580285a1692e782ebc902b44c884a71"},{"url":"https://git.kernel.org/stable/c/6bd17925bd6866027a6555db17905b9fc073d38d"},{"url":"https://git.kernel.org/stable/c/52f9db67f8f35f436366cf4980b4f0a2583d0ef0"},{"url":"https://git.kernel.org/stable/c/b778b6d095421619c331fd2d7751143cd5387103"},{"url":"https://git.kernel.org/stable/c/9dd5481f960e337b81d7dfe429529495c1c481c0"},{"url":"https://git.kernel.org/stable/c/f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e"}],"title":"net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"cpes":["cpe:/o:redhat:enterprise_linux:10"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 10","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:9"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 9","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:6"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 6","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:7"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 7","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:8"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 8","vendor":"Red Hat"}],"datePublic":"2026-05-27T00:00:00.000Z","descriptions":[{"lang":"en","value":"A flaw was found in the Linux kernel's IPv6 networking implementation, specifically within the `seg6` and `rpl` lwtunnels. A race condition can occur when handling destination cache entries, where a `NOREF` (no reference) destination object is used after it has been freed. This use-after-free vulnerability can lead to system instability or a denial of service (DoS) on systems configured with `PREEMPT_RT` (Preemptible Real-Time) kernel."}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-911","description":"Improper Update of Reference Count","lang":"en","type":"CWE"}]}],"references":[{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-46099"},{"name":"RHBZ#2481972","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2481972"},{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46099.json"}],"timeline":[{"lang":"en","time":"2026-05-27T00:00:00.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-05-27T00:00:00.000Z","value":"Made public."}],"title":"kernel: net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels","x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"},"providerMetadata":{"orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","shortName":"redhat-SADP","dateUpdated":"2026-06-30T12:10:13.161Z"}}]}}