{ "cvss": 8.1, "datePublished": "2026-05-27T14:17:31.557", "dateUpdated": "2026-09-09T13:20:15.450", "description": "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.", "id": "CVE-2026-46099", "raw": { "affected": [ { "affectedData": [ { "defaultStatus": "unaffected", "product": "Linux", "programFiles": [ "net/ipv6/rpl_iptunnel.c", "net/ipv6/seg6_iptunnel.c" ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [ { "lessThan": "51fef5a7c4d160839199e941929456ba21ddf73c", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "b258b849a580285a1692e782ebc902b44c884a71", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "6bd17925bd6866027a6555db17905b9fc073d38d", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "52f9db67f8f35f436366cf4980b4f0a2583d0ef0", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "b778b6d095421619c331fd2d7751143cd5387103", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "9dd5481f960e337b81d7dfe429529495c1c481c0", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" }, { "lessThan": "f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e", "status": "affected", "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "versionType": "git" } ] }, { "defaultStatus": "affected", "product": "Linux", "programFiles": [ "net/ipv6/rpl_iptunnel.c", "net/ipv6/seg6_iptunnel.c" ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [ { "status": "affected", "version": "4.12" }, { "lessThan": "4.12", "status": "unaffected", "version": "0", "versionType": "semver" }, { "lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.209", "versionType": "semver" }, { "lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.175", "versionType": "semver" }, { "lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.140", "versionType": "semver" }, { "lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.86", "versionType": "semver" }, { "lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.27", "versionType": "semver" }, { "lessThanOrEqual": "7.0.*", "status": "unaffected", "version": "7.0.4", "versionType": "semver" }, { "lessThanOrEqual": "*", "status": "unaffected", "version": "7.1", "versionType": "original_commit_for_fix" } ] } ], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67" }, { "affectedData": [ { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:10.2" ], "defaultStatus": "affected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 10", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "0:6.12.0-211.39.1.el10_2", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux_eus:10.0" ], "defaultStatus": "affected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 10.0 Extended Update Support", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "0:6.12.0-55.103.1.el10_0", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:rhel_e4s:9.2" ], "defaultStatus": "affected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "0:5.14.0-284.188.1.el9_2", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:rhel_e4s:9.2::nfv" ], "defaultStatus": "affected", "packageName": "kernel-rt", "product": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "0:5.14.0-284.188.1.rt14.473.el9_2", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:rhel_eus:9.6" ], "defaultStatus": "affected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 9.6 Extended Update Support", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "0:5.14.0-570.138.1.el9_6", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:6" ], "defaultStatus": "unaffected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 6", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:7" ], "defaultStatus": "unaffected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 7", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:7" ], "defaultStatus": "unaffected", "packageName": "kernel-rt", "product": "Red Hat Enterprise Linux 7", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "unaffected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "unaffected", "packageName": "kernel-rt", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "kernel", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "kernel-rt", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat" } ], "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c" } ], "configurations": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "6A1605BB-F7DD-4482-A80D-856944C7A446", "versionEndExcluding": "5.15.209", "versionStartIncluding": "4.12", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "92385813-D91D-480D-83A1-F423D2CBB2BA", "versionEndExcluding": "6.1.175", "versionStartIncluding": "5.16", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "A1A92866-F406-43B5-B2D1-CFC274753E9D", "versionEndExcluding": "6.6.140", "versionStartIncluding": "6.2", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "55DA1C62-9991-451E-B8A8-E0004E00F789", "versionEndExcluding": "6.12.86", "versionStartIncluding": "6.7", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "A10AC84F-C058-47D5-85B4-E6E51A613B74", "versionEndExcluding": "6.18.27", "versionStartIncluding": "6.13", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "CDB78D6D-22C3-4154-B0D0-94AF1CE5C2E3", "versionEndExcluding": "7.0.4", "versionStartIncluding": "6.19", "vulnerable": true }, { "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390", "vulnerable": true } ], "negate": false, "operator": "OR" } ] } ], "cveTags": [], "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." } ], "id": "CVE-2026-46099", "lastModified": "2026-09-09T13:20:15.450", "metrics": { "cvssMetricV31": [ { "cvssData": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary" }, { "cvssData": { "attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.3, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H", "version": "3.1" }, "exploitabilityScore": 1.8, "impactScore": 5.5, "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "type": "Secondary" } ] }, "published": "2026-05-27T14:17:31.557", "references": [ { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/51fef5a7c4d160839199e941929456ba21ddf73c" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/52f9db67f8f35f436366cf4980b4f0a2583d0ef0" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/6bd17925bd6866027a6555db17905b9fc073d38d" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/9dd5481f960e337b81d7dfe429529495c1c481c0" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/b258b849a580285a1692e782ebc902b44c884a71" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/b778b6d095421619c331fd2d7751143cd5387103" }, { "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": [ "Patch" ], "url": "https://git.kernel.org/stable/c/f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:45114" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:59662" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:59663" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:62568" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:64767" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/errata/RHSA-2026:65712" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://access.redhat.com/security/cve/CVE-2026-46099" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2481972" }, { "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46099.json" } ], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [ { "description": [ { "lang": "en", "value": "NVD-CWE-noinfo" } ], "source": "nvd@nist.gov", "type": "Primary" }, { "description": [ { "lang": "en", "value": "CWE-911" } ], "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "type": "Secondary" } ] }, "severity": "HIGH", "source": "nvd", "title": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix NOREF dst use in seg6 and rpl lwt..." }