CVE-2026-46099
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels seg6_input_core() and rpl_input() call ip6_route_input() which sets a NOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking dst_hold() unconditionally. On PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can release the underlying pcpu_rt between the lookup and the caching through a concurrent FIB lookup on a shared nexthop. Simplified race sequence: ksoftirqd/X higher-prio task (same CPU X) ----------- -------------------------------- seg6_input_core(,skb)/rpl_input(skb) dst_cache_get() -> miss ip6_route_input(skb) -> ip6_pol_route(,skb,flags) [RT6_LOOKUP_F_DST_NOREF in flags] -> FIB lookup resolves fib6_nh [nhid=N route] -> rt6_make_pcpu_route() [creates pcpu_rt, refcount=1] pcpu_rt->sernum = fib6_sernum [fib6_sernum=W] -> cmpxchg(fib6_nh.rt6i_pcpu, NULL, pcpu_rt) [slot was empty, store succeeds] -> skb_dst_set_noref(skb, dst) [dst is pcpu_rt, refcount still 1] rt_genid_bump_ipv6() -> bumps fib6_sernum [fib6_sernum from W to Z] ip6_route_output() -> ip6_pol_route() -> FIB lookup resolves fib6_nh [nhid=N] -> rt6_get_pcpu_route() pcpu_rt->sernum != fib6_sernum [W <> Z, stale] -> prev = xchg(rt6i_pcpu, NULL) -> dst_release(prev) [prev is pcpu_rt, refcount 1->0, dead] dst = skb_dst(skb) [dst is the dead pcpu_rt] dst_cache_set_ip6(dst) -> dst_hold() on dead dst -> WARN / use-after-free For the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without PREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release the pcpu_rt. Shared nexthop objects provide such a path, as two routes pointing to the same nhid share the same fib6_nh and its rt6i_pcpu entry. Fix seg6_input_core() and rpl_input() by calling skb_dst_force() after ip6_route_input() to force the NOREF dst into a refcounted one before caching. The output path is not affected as ip6_route_output() already returns a refcounted dst.
Severity
HIGH
CVSS score
8.1
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-27 14:17:31.557000
Last modified
2026-10-19 20:18:29.390000
View original CVE JSON
{
"id": "CVE-2026-46099",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-05-27T14:17:31.557",
"lastModified": "2026-10-19T20:18:29.390",
"vulnStatus": "Modified",
"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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/ipv6/rpl_iptunnel.c",
"net/ipv6/seg6_iptunnel.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "51fef5a7c4d160839199e941929456ba21ddf73c",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "b258b849a580285a1692e782ebc902b44c884a71",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "6bd17925bd6866027a6555db17905b9fc073d38d",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "52f9db67f8f35f436366cf4980b4f0a2583d0ef0",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "b778b6d095421619c331fd2d7751143cd5387103",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "9dd5481f960e337b81d7dfe429529495c1c481c0",
"versionType": "git",
"status": "affected"
},
{
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/ipv6/rpl_iptunnel.c",
"net/ipv6/seg6_iptunnel.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "4.12",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.12",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.209",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.175",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.140",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.86",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.27",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.0.4",
"lessThanOrEqual": "7.0.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.1",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
},
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"affectedData": [
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 10",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux:10.2"
],
"versions": [
{
"version": "0:6.12.0-211.39.1.el10_2",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 10.0 Extended Update Support",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux_eus:10.0"
],
"versions": [
{
"version": "0:6.12.0-55.103.1.el10_0",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/a:redhat:rhel_e4s:9.2"
],
"versions": [
{
"version": "0:5.14.0-284.188.1.el9_2",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel-rt",
"cpes": [
"cpe:/a:redhat:rhel_e4s:9.2::nfv"
],
"versions": [
{
"version": "0:5.14.0-284.188.1.rt14.473.el9_2",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 9.6 Extended Update Support",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/a:redhat:rhel_eus:9.6"
],
"versions": [
{
"version": "0:5.14.0-570.138.1.el9_6",
"lessThan": "*",
"versionType": "rpm",
"status": "unaffected"
}
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 6",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux:6"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 7",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux:7"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 7",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel-rt",
"cpes": [
"cpe:/o:redhat:enterprise_linux:7"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 8",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux:8"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 8",
"defaultStatus": "unaffected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel-rt",
"cpes": [
"cpe:/o:redhat:enterprise_linux:8"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 9",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel",
"cpes": [
"cpe:/o:redhat:enterprise_linux:9"
]
},
{
"vendor": "Red Hat",
"product": "Red Hat Enterprise Linux 9",
"defaultStatus": "affected",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "kernel-rt",
"cpes": [
"cpe:/o:redhat:enterprise_linux:9"
]
}
]
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"affectedData": [
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem",
"defaultStatus": "unknown",
"versions": [
{
"version": "0",
"lessThan": "*",
"versionType": "custom",
"status": "affected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"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",
"attackVector": "NETWORK",
"attackComplexity": "HIGH",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 2.2,
"impactScore": 5.9
},
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H",
"baseScore": 7.3,
"baseSeverity": "HIGH",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "LOW",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 5.5
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T15:19:34.914201Z",
"id": "CVE-2026-46099",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
]
},
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-416"
}
]
},
{
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-911"
}
]
}
],
"configurations": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.12",
"versionEndExcluding": "5.15.209",
"matchCriteriaId": "6A1605BB-F7DD-4482-A80D-856944C7A446"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.16",
"versionEndExcluding": "6.1.175",
"matchCriteriaId": "92385813-D91D-480D-83A1-F423D2CBB2BA"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.2",
"versionEndExcluding": "6.6.140",
"matchCriteriaId": "A1A92866-F406-43B5-B2D1-CFC274753E9D"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.7",
"versionEndExcluding": "6.12.86",
"matchCriteriaId": "55DA1C62-9991-451E-B8A8-E0004E00F789"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.13",
"versionEndExcluding": "6.18.27",
"matchCriteriaId": "A10AC84F-C058-47D5-85B4-E6E51A613B74"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.19",
"versionEndExcluding": "7.0.4",
"matchCriteriaId": "CDB78D6D-22C3-4154-B0D0-94AF1CE5C2E3"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*",
"matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390"
}
]
}
]
}
],
"references": [
{
"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": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
]
},
{
"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://cert-portal.siemens.com/productcert/html/ssa-784472.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46099.json",
"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
}
]
}