CVE-2026-74630 ipv6: prevent in6_dev_get() from resurrecting inet6_dev
A use-after-free in the Linux kernel IPv6 stack allows local attackers to execute code or escalate privileges via race conditions in device teardown.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74630?
CVE-2026-74630 is a high-severity use after free vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-74630?
How do I fix CVE-2026-74630?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-74630 being exploited?
There is no known exploitation of CVE-2026-74630 in the wild and no public exploit code.
Sources
Also known as AZL-97059, BELL-CVE-2026-74630, DEBIAN-CVE-2026-74630, GHSA-6g8v-5hwp-cmr2, UBUNTU-CVE-2026-74630.