EUVD-2026-64567
GHSA-6g8v-5hwp-cmr2
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local attack requiring low-privilege user; no user interaction; full kernel memory corruption impact across CIA; scope unchanged as kernel compromise stays on the same system.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionCVE.org
In 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.
AnalysisAI
Use-after-free in the Linux kernel's IPv6 stack allows a local low-privileged user to corrupt kernel memory with full high/integrity/availability impact. The race condition exists in in6_dev_get(), where dev->ip6_ptr is read under RCU and its refcount is then unconditionally incremented - device teardown can zero the pointer and drop the final reference between those two operations, resurrecting a freed inet6_dev object. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a local shell account with at minimum UID-level access (PR:L per CVSS). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | CVSS 7.8 (AV:L/AC:L/PR:L) indicates a local, low-complexity attack requiring only standard user privileges, with full confidentiality, integrity, and availability impact to the vulnerable system - consistent with a kernel use-after-free that can be leveraged for local privilege escalation or denial-of-service. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local user with a standard shell account (UID 1000) on a Linux host triggers the race by initiating IPv6 multicast operations (e.g., via ip6_mc_source()) while concurrently causing a network interface to be torn down - for instance, by rapidly adding and removing a virtual interface they control. The refcount resurrection corrupts kernel heap memory, which the attacker then leverages through the use-after-free primitive to overwrite sensitive kernel structures and escalate to root. … |
| Remediation | The primary fix is to upgrade to a patched kernel version: 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, 6.18.45, 7.1.9, or 7.2, depending on your branch. … Detailed patch versions, workarounds, and compensating controls in full report. |
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