CVE-2026-72429 (GCVE-0-2026-72429)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:44
VLAI
Title
ipv6: ioam: fix type confusion of dst_entry
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix type confusion of dst_entry IOAM uses a dummy dst_entry(null_dst) to mark that the destination should not be changed after the transformation. This dst is stored in the IOAM lwt state and may be passed to dst_cache_set_ip6(). However, the IPv6 dst cache path eventually calls rt6_get_cookie(), which treats the dst_entry as part of a struct rt6_info. Since the null_dst was embedded directly as a struct dst_entry in struct ioam6_lwt, this resulted in an invalid cast and rt6_get_cookie() reading fields from the wrong object. In practice, the wrong cookie is not used while dst->obsolete is zero, but rt6_get_cookie() may also access per-cpu value when rt->sernum is zero. In this case, rt->sernum aliases ioam6_lwt::cache::reset_ts, which can become zero, making this a potential invalid pointer access. Fix this by embedding a full struct rt6_info for the dummy IPv6 route and passing its dst member to the dst APIs.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 47ce7c854563fe8450e9cb8dcd62c6470e28076b , < ea24f911ead85ba3d570a31e37c52b6c949f6928 (git)
Affected: 47ce7c854563fe8450e9cb8dcd62c6470e28076b , < 5a3b2ee1e96d0580a8ed8deda6dfa430604f9ab0 (git)
Affected: 47ce7c854563fe8450e9cb8dcd62c6470e28076b , < 9ed19e11d2146076d117d51a940643990118449b (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ioam6_iptunnel.c"
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          "vendor": "Linux",
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              "versionType": "semver"
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              "versionType": "semver"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: fix type confusion of dst_entry\n\nIOAM uses a dummy dst_entry(null_dst) to mark that the destination should\nnot be changed after the transformation. This dst is stored in the IOAM lwt\nstate and may be passed to dst_cache_set_ip6().\n\nHowever, the IPv6 dst cache path eventually calls rt6_get_cookie(), which\ntreats the dst_entry as part of a struct rt6_info. Since the null_dst was\nembedded directly as a struct dst_entry in struct ioam6_lwt, this resulted\nin an invalid cast and rt6_get_cookie() reading fields from the wrong\nobject.\n\nIn practice, the wrong cookie is not used while dst-\u003eobsolete is zero, but\nrt6_get_cookie() may also access per-cpu value when rt-\u003esernum is\nzero. In this case, rt-\u003esernum aliases ioam6_lwt::cache::reset_ts, which\ncan become zero, making this a potential invalid pointer access.\n\nFix this by embedding a full struct rt6_info for the dummy IPv6 route and\npassing its dst member to the dst APIs."
        }
      ],
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:N - The flaw is in ioam6_output() on the IPv6 transmit path (lwtunnel_output\u2192dst_output), reachable when remotely sourced IPv6 packets are forwarded or locally output through an IOAM6 LWT route on internet-facing or LAN routers.\nAC:L - Once IOAM6 LWT inline routes exist, an attacker can reliably trigger the null_dst dst_cache_set_ip6() path by sending IPv6 traffic that misses the per-CPU dst cache, without races or uncontrollable memory layout.\nPR:N - Exploitation requires only the ability to send IPv6 packets; IOAM6 LWT route and namespace setup needs CAP_NET_ADMIN on the victim but is an operator deployment prerequisite, not attacker privilege.\nUI:N - No victim user action is required beyond normal network operation; crafted or high-volume IPv6 packets alone drive the vulnerable output path.\nS:U - Impact is kernel memory corruption and crash within the host kernel; it does not cross VM, container, or IOMMU security boundaries.\nC:H - Type confusion makes rt6_get_cookie() treat ioam6_lwt fields as rt6_info members and chase a misinterpreted fib6_info pointer via fib6_get_cookie_safe(), enabling out-of-bounds kernel memory reads.\nI:H - Casting a standalone dst_entry to rt6_info is type confusion that corrupts pointer interpretation and dst_cache cookie state, a class exploitable toward arbitrary kernel writes or control-flow hijack.\nA:H - The confused rt6_info layout can dereference invalid fib6_info/fib6_node pointers, causing kernel oops or panic; memory corruption in the networking fast path also risks host-wide denial of service."
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:44:08.737Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/ea24f911ead85ba3d570a31e37c52b6c949f6928"
        },
        {
          "url": "https://git.kernel.org/stable/c/5a3b2ee1e96d0580a8ed8deda6dfa430604f9ab0"
        },
        {
          "url": "https://git.kernel.org/stable/c/9ed19e11d2146076d117d51a940643990118449b"
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      "title": "ipv6: ioam: fix type confusion of dst_entry",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72429",
    "datePublished": "2026-08-15T05:56:45.530Z",
    "dateReserved": "2026-08-09T03:40:39.928Z",
    "dateUpdated": "2026-08-17T05:44:08.737Z",
    "state": "PUBLISHED"
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      "date": "2026-09-22",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: fix type confusion of dst_entry\n\nIOAM uses a dummy dst_entry(null_dst) to mark that the destination should\nnot be changed after the transformation. This dst is stored in the IOAM lwt\nstate and may be passed to dst_cache_set_ip6().\n\nHowever, the IPv6 dst cache path eventually calls rt6_get_cookie(), which\ntreats the dst_entry as part of a struct rt6_info. Since the null_dst was\nembedded directly as a struct dst_entry in struct ioam6_lwt, this resulted\nin an invalid cast and rt6_get_cookie() reading fields from the wrong\nobject.\n\nIn practice, the wrong cookie is not used while dst-\u003eobsolete is zero, but\nrt6_get_cookie() may also access per-cpu value when rt-\u003esernum is\nzero. In this case, rt-\u003esernum aliases ioam6_lwt::cache::reset_ts, which\ncan become zero, making this a potential invalid pointer access.\n\nFix this by embedding a full struct rt6_info for the dummy IPv6 route and\npassing its dst member to the dst APIs."
          }
        ],
        "id": "CVE-2026-72429",
        "lastModified": "2026-08-17T06:19:10.243",
        "metrics": {
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                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
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                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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        "vulnStatus": "Received"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:41:56+00:00",
      "cve": "CVE-2026-72429",
      "id": "CVE-2026-72429",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv6: ioam: fix type confusion of dst_entry",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72429.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-02T11:45:38Z",
      "cve": "CVE-2026-72429",
      "id": "CVE-2026-72429",
      "initial_release_date": "2026-08-28T00:59:30Z",
      "product_status:known_not_affected": "362",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72429",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72429.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.