GHSA-6G8V-5HWP-CMR2
Vulnerability from github – Published: 2026-08-22 18:30 – Updated: 2026-08-25 06:31In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent in6_dev_get() from resurrecting inet6_dev
in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally increments its refcount. Device teardown can clear the pointer and drop the last reference between these operations. The increment then resurrects an object whose RCU free has already been queued, so callers can use it after it is freed.
Use refcount_inc_not_zero() and return NULL when the object has already reached zero. RCU keeps the memory accessible through the attempted reference acquisition, and a successful increment pins the object for the caller.
An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3) kernel reproduced the invalid reference acquisition as UID 1000:
refcount_t: addition on 0; use-after-free. ip6_mc_source+0xef4/0x17e0
It was followed by the corresponding reference underflow in ip6_mc_source(). The supplied trace from the same unpatched revision additionally shows the access after the RCU read-side section ends:
BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0 Write of size 8 at addr ffff888015b50240 by task poc/1219
Bug found and triaged by OpenAI Security Research and validated by Trail of Bits.
{
"affected": [],
"aliases": [
"CVE-2026-74630"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-22T16:16:35Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: prevent in6_dev_get() from resurrecting inet6_dev\n\nin6_dev_get() reads dev-\u003eip6_ptr under RCU and then unconditionally\nincrements its refcount. Device teardown can clear the pointer and drop\nthe last reference between these operations. The increment then\nresurrects an object whose RCU free has already been queued, so callers\ncan use it after it is freed.\n\nUse refcount_inc_not_zero() and return NULL when the object has already\nreached zero. RCU keeps the memory accessible through the attempted\nreference acquisition, and a successful increment pins the object for\nthe caller.\n\nAn independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)\nkernel reproduced the invalid reference acquisition as UID 1000:\n\n refcount_t: addition on 0; use-after-free.\n ip6_mc_source+0xef4/0x17e0\n\nIt was followed by the corresponding reference underflow in\nip6_mc_source(). The supplied trace from the same unpatched revision\nadditionally shows the access after the RCU read-side section ends:\n\n BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0\n Write of size 8 at addr ffff888015b50240 by task poc/1219\n\nBug found and triaged by OpenAI Security Research and\nvalidated by Trail of Bits.",
"id": "GHSA-6g8v-5hwp-cmr2",
"modified": "2026-08-25T06:31:24Z",
"published": "2026-08-22T18:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74630"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0e243671bc7b8eaf00f83dd2f4367436dc0cff98"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/145812b678de9f3b59780173be3c0d22ed60dd93"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/14e812ab41df0cac033479da835ec9a5de633404"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1c206d461c680c3151daa3c89fc26eaf5bf98a7f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/680fbd7942185448eadb990a3d10a53eb946b702"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/785d908f8d21c8bc78b6fb2c2932ab662bf6918a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aedcfefdb5b7ed7f8a6196a3e68a25bdbe51d2f8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cc5bd568f9b7683e60841b6fd02c10d64535bd6e"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
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.
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.