GHSA-34FV-PGG7-6WVM
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In 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.
{
"affected": [],
"aliases": [
"CVE-2026-72429"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:16Z",
"severity": "CRITICAL"
},
"details": "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": "GHSA-34fv-pgg7-6wvm",
"modified": "2026-08-17T06:33:29Z",
"published": "2026-08-15T06:32:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72429"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5a3b2ee1e96d0580a8ed8deda6dfa430604f9ab0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9ed19e11d2146076d117d51a940643990118449b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ea24f911ead85ba3d570a31e37c52b6c949f6928"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- 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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.