CVE-2026-64542 (GCVE-0-2026-64542)
Vulnerability from cvelistv5 – Published: 2026-07-27 20:10 – Updated: 2026-08-19 16:28
VLAI
EPSS
VEX
Title
ipv6: ndisc: fix NULL deref in accept_untracked_na()
Summary
In the Linux kernel, the following vulnerability has been resolved:
ipv6: ndisc: fix NULL deref in accept_untracked_na()
accept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev)
and dereferences idev->cnf.accept_untracked_na without a NULL check,
even though its only caller ndisc_recv_na() already fetched and
NULL-checked idev for the same device.
Both reads of dev->ip6_ptr run in the same RCU read-side critical
section, but a concurrent addrconf_ifdown() can clear dev->ip6_ptr
between them: lowering the MTU below IPV6_MIN_MTU calls addrconf_ifdown()
without the synchronize_net() that orders the unregister path, so the
re-fetch returns NULL and oopses:
BUG: KASAN: null-ptr-deref in ndisc_recv_na (net/ipv6/ndisc.c:974)
Read of size 4 at addr 0000000000000364
Call Trace:
<IRQ>
ndisc_recv_na (net/ipv6/ndisc.c:974)
icmpv6_rcv (net/ipv6/icmp.c:1193)
ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479)
ip6_input_finish (net/ipv6/ip6_input.c:534)
ip6_input (net/ipv6/ip6_input.c:545)
ip6_mc_input (net/ipv6/ip6_input.c:635)
ipv6_rcv (net/ipv6/ip6_input.c:351)
</IRQ>
It is reachable by an unprivileged user via a network namespace.
Pass the caller's already validated idev instead of re-fetching it; the
idev stays alive for the whole RCU critical section, so it is safe even
after dev->ip6_ptr has been cleared.
Severity
No CVSS data available.
Assigner
References
6 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < e5ba3017e46f275ad347e762e8eecacec5efa41d
(git)
Affected: aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < 160d3f0d7a556ceae505dcab521a37057b4ce28f (git) Affected: aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < 62c719203cb521b64fab74da94a81bdde5c18808 (git) Affected: aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < a6450f7cfae57b382cbaf66a577765c9a88b3c58 (git) Affected: aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < 63d1c23764de2309cedbb779c75188d257a09d9b (git) Affected: aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 , < d186e942365acece7c56d39da05dd63bf95b280a (git) |
guessed | |
| Linux | Linux |
Affected:
6.0
Unaffected: 0 , < 6.0 (semver) Unaffected: 6.1.183 , ≤ 6.1.* (semver) Unaffected: 6.6.148 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
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"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv6/ndisc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"versionType": "git"
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"versionType": "git"
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"versionType": "git"
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"status": "affected",
"version": "aaa5f515b16b6b3e137779ffb4c9558bb58c1e75",
"versionType": "git"
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"versionType": "git"
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"versionType": "git"
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]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv6/ndisc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.0"
},
{
"lessThan": "6.0",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "6.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.148",
"versionStartIncluding": "6.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.97",
"versionStartIncluding": "6.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
"versionStartIncluding": "6.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "6.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ndisc: fix NULL deref in accept_untracked_na()\n\naccept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev)\nand dereferences idev-\u003ecnf.accept_untracked_na without a NULL check,\neven though its only caller ndisc_recv_na() already fetched and\nNULL-checked idev for the same device.\n\nBoth reads of dev-\u003eip6_ptr run in the same RCU read-side critical\nsection, but a concurrent addrconf_ifdown() can clear dev-\u003eip6_ptr\nbetween them: lowering the MTU below IPV6_MIN_MTU calls addrconf_ifdown()\nwithout the synchronize_net() that orders the unregister path, so the\nre-fetch returns NULL and oopses:\n\n BUG: KASAN: null-ptr-deref in ndisc_recv_na (net/ipv6/ndisc.c:974)\n Read of size 4 at addr 0000000000000364\n Call Trace:\n \u003cIRQ\u003e\n ndisc_recv_na (net/ipv6/ndisc.c:974)\n icmpv6_rcv (net/ipv6/icmp.c:1193)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479)\n ip6_input_finish (net/ipv6/ip6_input.c:534)\n ip6_input (net/ipv6/ip6_input.c:545)\n ip6_mc_input (net/ipv6/ip6_input.c:635)\n ipv6_rcv (net/ipv6/ip6_input.c:351)\n \u003c/IRQ\u003e\n\nIt is reachable by an unprivileged user via a network namespace.\n\nPass the caller\u0027s already validated idev instead of re-fetching it; the\nidev stays alive for the whole RCU critical section, so it is safe even\nafter dev-\u003eip6_ptr has been cleared."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:28:25.885Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/e5ba3017e46f275ad347e762e8eecacec5efa41d"
},
{
"url": "https://git.kernel.org/stable/c/160d3f0d7a556ceae505dcab521a37057b4ce28f"
},
{
"url": "https://git.kernel.org/stable/c/62c719203cb521b64fab74da94a81bdde5c18808"
},
{
"url": "https://git.kernel.org/stable/c/a6450f7cfae57b382cbaf66a577765c9a88b3c58"
},
{
"url": "https://git.kernel.org/stable/c/63d1c23764de2309cedbb779c75188d257a09d9b"
},
{
"url": "https://git.kernel.org/stable/c/d186e942365acece7c56d39da05dd63bf95b280a"
}
],
"title": "ipv6: ndisc: fix NULL deref in accept_untracked_na()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-64542",
"datePublished": "2026-07-27T20:10:34.994Z",
"dateReserved": "2026-07-19T15:36:31.795Z",
"dateUpdated": "2026-08-19T16:28:25.885Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-64542",
"date": "2026-10-31",
"epss": "0.00173",
"percentile": "0.06649"
},
"microsoft_vex": {
"current_release_date": "2026-08-09T01:41:15.000Z",
"cve": "CVE-2026-64542",
"id": "msrc_CVE-2026-64542",
"initial_release_date": "2026-08-09T01:41:15.000Z",
"product_status:fixed": "1",
"product_status:known_affected": "1",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "ipv6: ndisc: fix NULL deref in accept_untracked_na()",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-64542.json",
"version": "1"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv6/ndisc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
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"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
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}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.0"
},
{
"lessThan": "6.0",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ndisc: fix NULL deref in accept_untracked_na()\n\naccept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev)\nand dereferences idev-\u003ecnf.accept_untracked_na without a NULL check,\neven though its only caller ndisc_recv_na() already fetched and\nNULL-checked idev for the same device.\n\nBoth reads of dev-\u003eip6_ptr run in the same RCU read-side critical\nsection, but a concurrent addrconf_ifdown() can clear dev-\u003eip6_ptr\nbetween them: lowering the MTU below IPV6_MIN_MTU calls addrconf_ifdown()\nwithout the synchronize_net() that orders the unregister path, so the\nre-fetch returns NULL and oopses:\n\n BUG: KASAN: null-ptr-deref in ndisc_recv_na (net/ipv6/ndisc.c:974)\n Read of size 4 at addr 0000000000000364\n Call Trace:\n \u003cIRQ\u003e\n ndisc_recv_na (net/ipv6/ndisc.c:974)\n icmpv6_rcv (net/ipv6/icmp.c:1193)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479)\n ip6_input_finish (net/ipv6/ip6_input.c:534)\n ip6_input (net/ipv6/ip6_input.c:545)\n ip6_mc_input (net/ipv6/ip6_input.c:635)\n ipv6_rcv (net/ipv6/ip6_input.c:351)\n \u003c/IRQ\u003e\n\nIt is reachable by an unprivileged user via a network namespace.\n\nPass the caller\u0027s already validated idev instead of re-fetching it; the\nidev stays alive for the whole RCU critical section, so it is safe even\nafter dev-\u003eip6_ptr has been cleared."
}
],
"id": "CVE-2026-64542",
"lastModified": "2026-08-19T17:20:15.523",
"metrics": {},
"published": "2026-07-27T21:17:06.730",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/160d3f0d7a556ceae505dcab521a37057b4ce28f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/62c719203cb521b64fab74da94a81bdde5c18808"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/63d1c23764de2309cedbb779c75188d257a09d9b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a6450f7cfae57b382cbaf66a577765c9a88b3c58"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d186e942365acece7c56d39da05dd63bf95b280a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e5ba3017e46f275ad347e762e8eecacec5efa41d"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-10-29T10:47:30+00:00",
"cve": "CVE-2026-64542",
"id": "CVE-2026-64542",
"initial_release_date": "2026-07-27T00:00:00+00:00",
"product_status:known_affected": "91",
"product_status:known_not_affected": "185",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: ipv6: ndisc: fix NULL deref in accept_untracked_na()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64542.json",
"version": "3"
}
}
}
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