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CVE-2026-64542 (GCVE-0-2026-64542)

Vulnerability from cvelistv5 – Published: 2026-07-27 20:10 – Updated: 2026-08-19 16:28
VLAI
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
Impacted 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 Create a notification for this product.
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 Create a notification for this product.
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          "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."
        }
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      "providerMetadata": {
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          "url": "https://git.kernel.org/stable/c/d186e942365acece7c56d39da05dd63bf95b280a"
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      "title": "ipv6: ndisc: fix NULL deref in accept_untracked_na()",
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      "title": "ipv6: ndisc: fix NULL deref in accept_untracked_na()",
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      "version": "1"
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            "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",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-08-14T18:44:36+00:00",
      "cve": "CVE-2026-64542",
      "id": "CVE-2026-64542",
      "initial_release_date": "2026-07-27T00:00:00+00:00",
      "product_status:known_affected": "90",
      "product_status:known_not_affected": "184",
      "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"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:46:21Z",
      "cve": "CVE-2026-64542",
      "id": "CVE-2026-64542",
      "initial_release_date": "2026-07-28T17:08:04Z",
      "product_status:known_affected": "125",
      "product_status:known_not_affected": "251",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64542",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64542.json",
      "version": "7"
    }
  }
}



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